Communication control apparatus and wireless communication apparatus

ABSTRACT

[Solution] Provided is a communication control apparatus including: a calculation unit configured to calculate a transmit power to be allocated, including a nominal transmit power and a margin for interference avoidance, for one or more secondary systems that secondarily use frequency channels protected for a primary system; and a determination unit configured to determine a variation in a number of secondary systems, and cause the calculation unit to adjust the margin for interference avoidance on a basis of the determined variation.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.15/978,624, filed May 14, 2018, which is a continuation of U.S.application Ser. No. 14/895,160, filed on Dec. 1, 2015 (now U.S. Pat.No. 10,004,044), which is based on PCT application No.PCT/JP2014/066410, filed on Jun. 20, 2014, and claims priority toJapanese Patent Application 2013-171018, filed on Aug. 21, 2013, theentire contents of each of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a communication control apparatus anda wireless communication apparatus.

BACKGROUND ART

The secondary usage of frequencies is being discussed as onecountermeasure for relieving the depletion of frequency resources in thefuture. Secondary usage of frequencies refers to another systemsecondarily using some or all of the frequency channel preferentiallyallocated to a first system. Generally, the system to which thefrequency channel is preferentially allocated is called the primarysystem, while the system that secondarily uses the frequency channel iscalled the secondary system. A typical example of a secondary system isa cognitive radio system.

TV white spaces are an example of frequency channels whose secondaryusage is being discussed (see Non-Patent Literature 1). TV white spacesrefer to channels, from among the frequency channels allocated to atelevision broadcasting system that acts as a primary system, which arenot being used by that television broadcasting system depending on thegeographical area. By opening up these TV white spaces to secondarysystems, efficient frequency resource utilization may be realized.Non-Patent Literature 1 defines the technical requirements andoperational requirements of a white space device (WSD) using a secondarysystem. A device that manages a secondary system is also called a masterWSD, while a device that participates in a secondary system is alsocalled a slave WSD.

During secondary usage of a frequency band, the secondary systemordinarily is demanded to be operated so as not to exert harmfulinterference on the primary system. One important technology for thispurpose is transmit power control. For example, Patent Literature 1 andPatent Literature 2 disclose technology for restraining the aggregatedinterference that multiple secondary systems exert on the primary systemto an allowed level.

CITATION LIST Patent Literature

-   Patent Literature 1: JP 2012-151815A-   Patent Literature 2: JP 2013-78096A

Non-Patent Literature

-   Non-Patent Literature 1: ECC Electronic Communications Committee),    “Technical and operational requirements for the operation of white    space devices under geo-location approach”, ECC REPORT 186, January    2013

SUMMARY OF INVENTION Technical Problem

However, the calculation cost for evaluating the aggregated interferenceexerted on the primary system increases as the number of secondarysystems increases. For example, if the number of master WSDs secondarilyusing the white space for the same primary system doubles, thecalculation cost may quadruple. If the calculation for interferenceevaluation does not finish within an allowed time, power allocation isunable to track variation in the number of secondary systems, and thevalidity of control possibly may be lost.

Consequently, it is desirable to realize a mechanism capable ofachieving both prevention of harmful interference and promptness ofpower allocation under conditions in which multiple secondary systemsmay be managed.

Solution to Problem

According to the present disclosure, there is provided a communicationcontrol apparatus including: a calculation unit configured to calculatea transmit power to be allocated, including a nominal transmit power anda margin for interference avoidance, for one or more secondary systemsthat secondarily use frequency channels protected for a primary system;and a determination unit configured to determine a variation in a numberof secondary systems, and cause the calculation unit to adjust themargin for interference avoidance on a basis of the determinedvariation.

According to the present disclosure, there is provided a communicationcontrol apparatus including: a communication unit configured tocommunicate with a master device of one or more secondary systems thatsecondarily use frequency channels protected for a primary system; and acontrol unit configured to signal, on a basis of information acquiredfrom a data server that calculates an allocated transmit power for thesecondary systems including a nominal transmit power and a margin forinterference avoidance adjusted on a basis of variation in a number ofsecondary systems, parameters for specifying the allocated transmitpower to the master device via the communication unit.

According to the present disclosure, there is provided a wirelesscommunication apparatus that operates and manages a secondary systemthat secondarily uses a frequency channel protected for a primarysystem, the wireless communication apparatus including: a communicationunit configured to receive signaling of parameters for specifying anallocated transmit power based on information acquired from a dataserver that calculates the allocated transmit power for the secondarysystem including a nominal transmit power and a margin for interferenceavoidance adjusted on a basis of variation in a number of secondarysystems; and a communication control unit configured to control wirelesscommunication between the wireless communication apparatus and one ormore terminal apparatuses according to the allocated transmit powerspecified using the parameters.

Advantageous Effects of Invention

According to the technology in accordance with the present disclosure,it is possible to achieve both prevention of harmful interferenceprevention and promptness of power allocation under conditions in whichmultiple secondary systems may be managed.

Note that the effects described above are not necessarily limited, andalong with or instead of the effects, any effect that is desired to beintroduced in the present specification or other effects that can beexpected from the present specification may be exhibited.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory diagram for describing an overview of acommunication control system according to an embodiment.

FIG. 2 is an explanatory diagram for describing an example of a scenarioin which secondary systems increase.

FIG. 3 is an explanatory diagram for describing another example of ascenario in which secondary systems increase.

FIG. 4 is a graph illustrating an example of the relationship betweenthe number of secondary systems and the calculation cost of transmitpower to allocate.

FIG. 5 is an explanatory diagram for describing an example of delayedpower allocation.

FIG. 6 is a block diagram illustrating an example of a logicalconfiguration of a communication control apparatus according to anembodiment.

FIG. 7A is a flowchart illustrating a first example of the flow of apower distribution process according to an embodiment.

FIG. 7B is a flowchart illustrating a second example of the flow of apower distribution process according to an embodiment.

FIG. 7C is a flowchart illustrating a third example of the flow of apower distribution process according to an embodiment.

FIG. 7D is a flowchart illustrating a fourth example of the flow of apower distribution process according to an embodiment.

FIG. 8 is a flowchart illustrating an example of the flow of a marginadjustment process which may be executed during the power distributionprocess illustrated in FIGS. 7A to 7C.

FIG. 9A is a first sequence diagram illustrating an example of asignaling sequence in a system according to an embodiment.

FIG. 9B is a second sequence diagram illustrating an example of asignaling sequence in a system according to an embodiment.

FIG. 10 is a block diagram illustrating an example of a logicalconfiguration of a wireless communication apparatus according to anembodiment.

FIG. 11 is an explanatory diagram for describing another example of asystem model.

FIG. 12 is a block diagram illustrating an example of a schematicconfiguration of a GLDB.

FIG. 13 is a block diagram illustrating an example of a schematicconfiguration of an eNB.

FIG. 14 is a block diagram illustrating an example of a schematicconfiguration of a smartphone.

FIG. 15 is a block diagram illustrating an example of a schematicconfiguration of a car navigation apparatus.

DESCRIPTION OF EMBODIMENTS

Hereinafter, (a) preferred embodiment(s) of the present disclosure willbe described in detail with reference to the appended drawings. In thisspecification and the drawings, elements that have substantially thesame function and structure are denoted with the same reference signs,and repeated explanation is omitted.

Also, the description will proceed in the following order.

-   -   1. Overview of system        -   1-1. System model using GLDB        -   1-2. Change in number of secondary systems        -   1-3. Delayed power allocation    -   2. Examples of power calculation model        -   2-1. Existing technique        -   2-2. Simpler technique    -   3. Exemplary configuration of communication control apparatus        -   3-1. Component configuration        -   3-2. Modifications    -   4. Process flows        -   4-1. Power distribution process        -   4-2. Margin adjustment process        -   4-3. Signaling sequence    -   5. Exemplary configuration of wireless communication apparatus    -   6. Another example of system model    -   7. Applications        -   7-1. Example application related to communication control            apparatus        -   7-2. Example application related to wireless communication            apparatus    -   8. Conclusion

1. Overview of System 1-1. System Model Using GLDB

FIG. 1 is an explanatory diagram for describing a summary of acommunication control system 1 according to an embodiment of technologyin accordance with the present disclosure. The communication controlsystem 1 includes a primary transceiver 10, one or more wirelesscommunication apparatuses 20 a, 20 b, and so on, and a communicationcontrol apparatus 100.

The primary transceiver 10 is a transceiver installed to manage aprimary system on a frequency channel that has been legally licensed orassigned usage rights. The primary transceiver 10 transmits wirelesssignals of the primary system to primary terminals (not illustrated)positioned inside a service area 11. The primary system may be atelevision broadcasting system such as a Digital VideoBroadcasting—Terrestrial (DVB-T) system, for example. In this case, aprimary receiver is a receiver including a television antenna and atuner (also called an incumbent receiver). Additionally, the primarysystem may also be a mobile communication system that operates inaccordance with a communication scheme such as LTE, LTE-A, GSM, UMTS,W-CDMA, CDMA200, WiMAX, WiMAX 2, or IEEE 802.16. Additionally, theprimary system may also be another type of wireless communication systemsuch as an aircraft radio system (for example, the Aeronautical RadioNavigation Service (ARNS)).

The primary transceiver 10 is connected to a core network 15. The corenetwork 15 includes multiple control nodes that respectively have rolessuch as user information management, terminal mobility management,packet forwarding and gateway.

Each of the wireless communication apparatuses 20 a, 20 b, and so on isa master device that manages a secondary system by secondarily using afrequency channel protected for the primary system. Each of the wirelesscommunication apparatuses 20 a, 20 b, and so on may be the master WSDdescribed in Non-Patent Literature 1, for example, or some other type ofdevice, such as a small-cell base station or a wireless access point.Small cells may include femtocells, nanocells, picocells, microcells,and the like.

Note that in this specification, when the wireless communicationapparatuses 20 a, 20 b, and so on are not being distinguished from eachother, these apparatuses will be collectively referred to as thewireless communication apparatus 20 by omitting the trailing letters ofthe reference signs. This applies similarly to the other structuralelements.

The wireless communication apparatus 20 transmits and receives wirelesssignals to and from a slave device (not illustrated) positioned near thewireless communication apparatus 20 itself. When the secondary systemexists in the vicinity of the service area 11, the wireless signals ofthe secondary system interfere with the primary terminals. When multiplesecondary systems exist as in the example of FIG. 1, the interferenceobserved at a primary terminal may be aggregated.

The wireless communication apparatus 20 connects to a packet datanetwork (PDN) 16 via backhauling. The backhauling may be a wired link ora wireless link. The PDN 16 connects to the core network 15 via agateway (not illustrated).

The communication control apparatus 100 is a data server disposed on thePDN 16. The communication control apparatus 100 may be the geo-locationdatabase (GLDB) described in Non-Patent Literature 1, for example, orsome other type of server. The communication control apparatus 100 isnot limited to the example of FIG. 1, and may also be disposed on thecore network 15. Also, a functional entity including functions similarto the communication control apparatus 100 may also be implemented inthe primary transceiver 10. The communication control apparatus 100allows transmit power to each secondary system so that the aggregatedinterference caused by wireless signals from one or more secondarysystems does not exert harmful effects on the primary system. Forexample, the wireless communication apparatus 20, which is the masterdevice of each secondary system, transmits an activation request to thecommunication control apparatus 100 via backhauling when starting theoperation and management of the system. The communication controlapparatus 100, in response to receiving the activation request,calculates the transmit power that should be allocated to each secondarysystem. Subsequently, the communication control apparatus 100 notifiesthe wireless communication apparatus 20 of the transmit power allocationresult (as well as other information, such as a list of channelsavailable for use). Through such a procedure, the operation andmanagement of secondary systems become possible.

Typically, the aggregated interference caused by wireless signals fromsecondary systems is estimated as an interference level at some location(called a reference point) inside the service area 11. Subsequently, thecommunication control apparatus 100 calculates the transmit power toallocate to each secondary system so that the estimated interferencelevel does not exceed an allowed level. The reference point may also bea location on a protection contour of the service area 11 where thedistance from each wireless communication apparatus 20 is the shortest,for example. Alternatively, the reference point may also be the locationwhere the primary terminal the shortest distance away from each wirelesscommunication apparatus 20 is present. In the example of FIG. 1, thereference points 22 a, 22 b, and so on corresponding to each of thewireless communication apparatuses 20 a, 20 b, and so on are configuredon a protection contour of the service area 11.

For example, the power distribution method described in PatentLiterature 1 or the margin minimization method (a technique using aflexible minimized margin) described in Non-Patent Literature 2 has theadvantage of being able to allocate a larger transmit power to asecondary system as a result of configuring as small a margin forinterference avoidance as possible, and thus raise the throughput of thesecondary system. However, with these techniques, since the aggregatedinterference is evaluated at all reference points, the calculation costfor calculating the transmit power to allocated increases as the numberof secondary systems increases. In the simplest example, the calculationcost may increase on the order of the square of the number of secondarysystems (the product of the number of reference points and the number ofsecondary systems). Additionally, if factors such as the process for theconfiguration of the reference points and the signaling overhead arealso considered, the calculation cost for calculating the transmit powerto allocate becomes non-negligible.

1-2. Change in Number of Secondary Systems

A change in the number of secondary systems may occur due to variousfactors. For example, referring to FIG. 2 in contrast to FIG. 1, thewireless communication apparatuses 20 h, 20 i, and 20 j are newlyincluded in the communication control system 1. Each of the wirelesscommunication apparatuses 20 h, 20 i, and 20 j is also a master devicethat operates and manages a secondary system. As a result, the number ofsecondary systems increases from six to nine. The wireless communicationapparatuses 20 h, 20 i, and 20 j may be devices that moved from anotherplace to the vicinity of the service area 11, or devices that returnedfrom sleep mode to active mode. In the recent mobile environment with awide proliferation of mobile devices in which fine-grained sleep controlis often desired for power savings, such changes in the number ofsecondary systems occur frequently. Consequently, it is desirable forthe allocation of transmit power to secondary systems to be capable ofadequately tracking changes in the number of secondary systems.

The left half of FIG. 3 illustrates a primary transceiver 10 a thatoperates and manages a primary system inside a service area 11 a in ageographical region 3 a. A communication control apparatus 100 a has theauthority to allocate transmit power to one or more secondary systemsthat secondarily use a frequency channel for the purpose of the primarytransceiver 10 a inside the geographical region 3 a. The right half ofFIG. 3 illustrates a primary transceiver 10 b that operates and managesa primary system inside a service area 11 b in a geographical region 3b. A communication control apparatus 100 b has the authority to allocatetransmit power to one or more secondary systems that secondarily use afrequency channel for the purpose of the primary transceiver 10 b insidethe geographical region 3 b. Herein, depending on the positionalrelationships of devices between the regions or the conditions oftransmit power allocation, there is a possibility that the communicationcontrol apparatus 100 a may need to account for interference signalsfrom secondary systems inside the geographical region 3 b. In suchcases, the number of secondary systems that must be introduced into thepower allocation calculation may also increase.

FIG. 4 is a graph illustrating an example of the relationship betweenthe number of secondary systems and the calculation cost of transmitpower to allocate. The horizontal axis of FIG. 4 indicates the number ofactive primary WDSs, or in other words the number of secondary systemsthat must be introduced into the power allocation calculation. Thevertical axis of FIG. 4 indicates the calculation cost of powerallocation as estimated according to a certain simulation model. As FIG.4 demonstrates, the calculation cost increases as the number of masterdevices of secondary systems becomes larger.

1-3. Delayed Power Allocation

As discussed above, it is desirable for the allocation of transmit powerto secondary systems to be capable of adequately tracking changes in thenumber of secondary systems. However, if the calculation cost becomesgreat, there is a risk that the power allocation calculation may notfinish within a designated calculation period, and the allocation oftransmit power becoming may become delayed.

FIG. 5 is an explanatory diagram for describing an example of delayedpower allocation. In the example of FIG. 5, the calculation of powerallocation is executed periodically in a period D_(CP) along the timeaxis in the horizontal direction. The period D_(CP) may be defined inunits of subframes, radio frames, milliseconds, seconds, or the like,for example.

At time T₀, X₀ secondary systems are activated. The transmit power to beallocated to the X₀ secondary systems is calculated over a time durationDo. Since the time duration Do is shorter than the period D_(CP), eachsecondary system is notified of the power allocation result in a timelymanner. At time T₁(=T₀+D_(CP)), X₁ secondary systems are additionallyactivated. The transmit power to be allocated to the X₀+X₁ secondarysystems is calculated over a time duration D₁. Since the time durationD₁ is shorter than the period D_(CP), each secondary system is notifiedof the power allocation result in a timely manner. At time T₂, X₂secondary systems are additionally activated. The transmit power to beallocated to the X₀+X₁+X₂ secondary systems is calculated over a timeduration D₂. Since the time duration D₂ is longer than the periodD_(CP), the notification to each secondary system of the powerallocation result is delayed until after the next calculation periodstarts at time T₃. At time T₃, X₃ secondary systems are additionallyactivated. The transmit power to be allocated to the X₀+X₁+X₂+X₃secondary systems is calculated over a time duration D₃. Thenotification to each secondary system of the power allocation result isdelayed even further than the previous time. At time T₄, X₀ secondarysystems are deactivated. The transmit power to be allocated to theX₁+X₂+X₂+X₃ secondary systems is calculated over a time duration D₄.Even though the time duration D₄ is shorter than the period D_(CP), theeffects of the delay from the previous time still remain, and thus thenotification to each secondary system of the power allocation result isdelayed until after the next calculation period starts at time T₅.

Such delay may lead various adverse effects, such as a loss ofcommunication opportunities for the secondary systems because transmitpower is not allocated, a drop in resource utilization efficiency, andthe production of harmful interference caused by the power allocationnot being updated in a timely manner. Accordingly, in the embodimentdiscussed later, to counteract these adverse effects and achieve bothprevention of harmful interference and promptness of power allocation,there is realized a mechanism that adaptively switches the algorithm forpower allocation between an existing technique having a largecalculation cost, and a simpler technique of estimating the margin. Theexisting technique having a large calculation cost may be the powerdistribution method described in Patent Literature 1 or the marginminimization method described in Non-Patent Literature 2, for example.

2. Examples of Power Calculation Model 2-1. Existing Technique

Herein, a power calculation model that resembles the model described inNon-Patent Literature 2 will be described briefly.

In this power calculation model, the transmit power to allocate to eachsecondary system is calculated by using a nominal transmit power of therelevant secondary system and a margin for interference avoidance. Thenominal transmit power P_(IB) ^(SingleWSD) of a secondary system mayalso be called the maximum radiated power, and be calculated accordingto the following formula. The reference point in this case is theclosest location on the protection contour from the master device (orthe position of the closest primary transceiver). When a primarytransceiver is not present, the reference point may also be set toinfinity. Note that in this specification, formulas are expressed indecibel form as a general rule.[Math. 1]P _(IB) ^(SingleWSD) ≤m _(Z) −m _(G) −r(df)−SM  (1)

In Expression (1), m_(Z) is the minimum receiving sensitivity of aprimary terminal, m_(G) is the path gain, r(df) is the protection ratiocorresponding to a discrete frequency df, and SM is the shadowingmargin. The path gain may depend on the distance between the locationwhere the device is present and the reference point, and the antennaheight of the device. The protection ratio may depend on the frequencychannel to be secondarily used. The transmit power P_(IB) ^(WSD) toallocate to each secondary system is calculated by subtracting theinterference avoidance margin IM from the nominal transmit poweraccording to the following expression, so that the level of aggregatedinterference from multiple secondary systems does not become harmful atthe reference point.[Math. 2]P _(IB) ^(WSD) ≤P _(IB) ^(SingleWSD) −IM  (2)

Whereas the nominal transmit power P_(IB) ^(SingleWSD) is different foreach secondary system, in principle the interference avoidance margin IMmay be shared in common for all secondary systems. To calculate theinterference avoidance margin IM, the three techniques of the fixedmargin method, the flexible margin method, and the margin minimizationmethod are known.

In the fixed margin method, the interference avoidance margin IM iscalculated according to the following expression using the total numberN_(Potential) of secondary systems.[Math. 3]IM=10 log₁₀(N _(potential))  (3)

In the flexible margin method, the interference avoidance margin IM iscalculated according to the following expression using the numberN_(Active)(f_(WSD)) of active secondary system per channel. Note thatherein, an active secondary system may mean simply an activated system,or mean a system using a transmit power exceeding some base value in thechannel f_(WSD).

$\begin{matrix}\left\lbrack {{Math}.\mspace{11mu} 4} \right\rbrack & \; \\{{IM} = {10\;{\log_{10}\left( {\max\limits_{f}\left( {N_{Active}\left( f_{WSD} \right)} \right)} \right)}}} & (4)\end{matrix}$

In the margin minimization method, the interference avoidance margin IMis calculated according to the following expression using the totalnumber N_(Potential) of secondary systems and a margin reduction term a.[Math. 5]IM=10 log₁₀(N _(Potential))−α  (5)

where α=m_(Z)−r(0)−SM−I_(Agg,max)

Herein, r(0) represents the protection ratio of a discrete frequencyzero, or in other words a co-channel, while I_(Agg,max) represents theaggregated interference quantity at the reference point whereinterference is greatest. This aggregated interference quantity may alsoinclude interference quantities from other systems. In the fixed marginmethod and the flexible margin method, the primary system is carefullyprotected, but in the margin minimization method, the throughput of thesecondary system is raised by the contribution of the margin reductionterm a, and the resource utilization efficiency may be improved.However, in the margin minimization method, deriving the aggregatedinterference quantity I_(Agg,max) demands evaluation of the levels ofaggregated interference at all reference points.

2-2. Simpler Technique (1) Relationship Between Number of SecondarySystems and Margin Adjustment

According to an embodiment, when the number of secondary systems changesafter transmit power is allocated to the secondary systems according tothe power calculation model discussed above, the previously calculatedtransmit power may be adjusted on the basis of the variation in thenumber of secondary systems. The adjustment of transmit power isconducted simply by adjusting the interference avoidance margin IM onthe basis of the variation in the number of secondary systems. Thefollowing relational expression holds true among the already-allocatedinterference avoidance margin that was calculated at a previous basepoint in time (according to the margin minimization method, forexample), the adjusted interference avoidance margin IM, and the marginadjustment.[Math. 6]IM′=IM _(Base) +dM  (6)

Herein, IM′ is the adjusted interference avoidance margin, IM_(Base) isthe interference avoidance margin at the base point in time (the basevalue of adjustment), and dM is the margin adjustment.

At this point, provided that N_(WSD) is the number of secondary systemsat the base point in time, and N_(WSD_VAR) is the variation in thenumber of secondary systems since the base point in time, the marginadjustment dM may be expressed as follows from Expressions (5) and (6).Note that the number of secondary systems and the variation thereof mayrefer to active devices only, or to the total number.

$\begin{matrix}{\begin{matrix}{{dM} = {{IM}^{\prime} - {IM}_{Base}}} \\{= {{10\;{\log_{10}\left( {N_{WSD} + N_{{WSD}\;\_\;{VAR}}} \right)}} - \alpha_{Adj} -}} \\{\left( {{10\;{\log_{10}\left( N_{WSD} \right)}} - \alpha_{Prev}} \right)} \\{= {{10\;{\log_{10}\left( \frac{N_{WSD} + N_{{WSD}\;\_\;{VAR}}}{N_{WSD}} \right)}} - \alpha_{Adj} + \alpha_{Prev}}} \\{= {{10{\log_{10}\left( \frac{N_{WSD} + N_{{WSD}\;\_\;{VAR}}}{N_{WSD}} \right)}} + {10\log_{10}}}} \\{\left( {Y + {{{sgn}\left( N_{{WDS}\;\_\;{VAR}} \right)} \cdot 10^{\frac{dI}{10}}}} \right) - {10{\log_{10}(Y)}}} \\{= {10{\log_{10}\left( {\frac{N_{WSD} + N_{{WSD}\;\_\;{VAR}}}{N_{WSD}} \cdot \frac{Y + {{{sgn}\left( N_{{WDS}\;\_\;{VAR}} \right)} \cdot 10^{\frac{dI}{10}}}}{Y}} \right)}}}\end{matrix}\mspace{20mu}{{{where}\mspace{14mu}{{sgn}(x)}} = \left\{ {{\begin{matrix}{{1\text{:}\mspace{11mu} x} > 0} \\{{0\text{:}\mspace{14mu} x} = 0} \\{{{- 1}\text{:}\mspace{11mu} x} < 0}\end{matrix}\;\mspace{20mu}{and}\mspace{14mu} Y} = 10^{\frac{I_{{Agg},\max}}{10}}} \right.}} & (7)\end{matrix}$

In Expression (7), dI represents the magnitude of the variation in theaggregated interference quantity I_(Agg,max) corresponding to thevariation N_(WSD_VAR) in the number of secondary systems (hereinaftercalled the estimated interference variation). To reduce the calculationcost, the estimated interference variation dI is not calculatedprecisely, but instead estimated simply on the basis of the variationN_(WSD_VAR) in the number of secondary systems. Several techniques forcalculating the estimated interference variation dI are described below.

(2-1) Calculation of Estimated Interference Variation (First Technique)

In the first technique, the estimated interference variation dI isestimated using a table that defines a mapping between the variationN_(WSD_VAR) in the number of secondary systems and the estimatedinterference variation dI. Table 1 and Table 2 respectively illustrateexamples of mapping tables. In Table 1, the estimated interferencevariation dI is mapped directly to the variation N_(WSD_VAR) in thenumber of secondary systems. On the other hand, in Table 2, theestimated interference variation dI is mapped to a range to which thevariation N_(WSD_VAR) in the number of secondary systems belongs.

TABLE 1 Example of mapping between variation N_(WSD)_VAR in number ofsecondary systems and estimated interference variation dI N_(WSD)_VAR dI(dB) K₁ dI₁ K₂ dI₂ K₃ dI₃ . . . . . . K_(x) dI_(X)

TABLE 2 Another example of mapping between variation N_(WSD)_VAR innumber of secondary systems and estimated interference variation dIRange of N_(WSD)_VAR dI (dB) [K₁, K₂] dI₁ [K₂, K₃] dI₂ [K₃, K₄] dI₃ . .. . . . [K_(X−1), K_(X)] dI_(X)

According to the first technique, by performing a lookup in a predefinedmapping table, the estimated interference variation dI may be derivedwith a small calculation cost.

(2-2) Calculation of Estimated Interference Variation (Second Technique)

In the second technique, the estimated interference variation dI isestimated on the basis of an assumption that the number of secondarysystems and the aggregated interference quantity are proportional. Underthis assumption, the estimated interference variation dI may beexpressed as in the following expression.

$\begin{matrix}\left\lbrack {{Math}.\mspace{11mu} 8} \right\rbrack & \; \\{{dI} = {10\;{\log_{10}\left( {\frac{N_{{WSD}\;\_\;{VAR}}}{N_{WSD}} \cdot Y} \right)}}} & (8)\end{matrix}$

Substituting Expression (8) into Expression (7), the relationalexpression between the number of secondary systems and the marginadjustment may be transformed as follows.

$\begin{matrix}\left\lbrack {{Math}.\mspace{11mu} 9} \right\rbrack & \; \\\begin{matrix}{{dM} = {10{\log_{10}\begin{pmatrix}{\frac{N_{WSD} + N_{{WSD}\;\_\;{VAR}}}{N_{WSD}} \cdot} \\\frac{Y + {{{sgn}\left( N_{{WDS}\;\_\;{VAR}} \right)} \cdot \left( {\frac{N_{{WSD}\;\_\;{VAR}}}{N_{WSD}} \cdot Y} \right)}}{Y}\end{pmatrix}}}} \\{= {10{\log_{10}\left( {\frac{N_{{WSD}\;} + N_{{WSD}\;\_\;{VAR}}}{N_{WSD}} \cdot \left( {1 + \frac{N_{{WSD}\;\_\;{VAR}}}{N_{WSD}}} \right)} \right)}}} \\{= {20{\log_{10}\left( {1 + \frac{N_{{WSD}\;\_\;{VAR}}}{N_{WSD}}} \right)}}}\end{matrix} & (9)\end{matrix}$

Consequently, in this case, the margin adjustment dM may be computedsimply, using only the number N_(WSD) of secondary systems at the basepoint in time and the variation N_(WSD_VAR) in the number of secondarysystems.

Note that by incorporating the approach of the flexible margin methodinto Expression (7), the margin adjustment dM may also be computed as inthe following expression.

$\begin{matrix}{\mspace{76mu}\left\lbrack {{Math}.\mspace{11mu} 10} \right\rbrack} & \; \\{{dM} = {10\;{\log_{10}\left( {\left( {1 + {\frac{N_{{WSD}\;\_\;{VAR}}}{N_{WSD}} \cdot \frac{\max\limits_{m}\left( {f_{m}\left( N_{{WSD}\;\_\;{VAR}} \right)} \right)}{N_{channel}}}} \right) \cdot \frac{N_{WSD} + N_{{WSD}\;\_\;{VAR}}}{N_{WSD}}} \right)}}} & (10)\end{matrix}$

In Expression (10), f_(m)(N_(WSD_VAR)) expresses the number of secondarysystems to which the mth frequency channel is allocated from among thevariation N_(WSD_VAR) in the number of secondary systems.

(2-3) Calculation of Estimated Interference Variation (Third Technique)

In the third technique, the estimated interference variation dI isestimated according to the following expression as a worst case.

$\begin{matrix}\left\lbrack {{Math}.\mspace{11mu} 11} \right\rbrack & \; \\{{dI} = {10\;{\log_{10}\left( {10^{\frac{I_{TH}}{10}} - 10^{\frac{I_{{Agg},\max}}{10}}} \right)}}} & (11)\end{matrix}$

In Expression (11), I_(TH) represents a threshold value that maycorrespond to the maximum value of the aggregated interference allowedby the primary terminal.

(3) Technique for Counting Number of Secondary Systems

The number of secondary systems in the power calculation model describedin this section may be based on one or both of the number of masterdevices and the number of slave devices in the secondary systems. Forexample, when the secondary systems are operated and managed accordingto a time-division scheme, and the slave devices use a transmit powerapproximately equal to (or lower than) the transmit power of the masterdevice, it is sufficient to count only the number of master devices asthe number of secondary systems. On the other hand, when a master deviceand a slave device potentially may transmit signals at the same time,for example, the calculation of a safe power may be ensured by countingboth master devices and slave devices as the number of secondarysystems.

These numbers of devices may also be calculated by including weightsdepending on the device configuration. As used herein, the deviceconfiguration may include one or more from among the antenna height, thetransmit power (which may be a maximum or desired transmit power, or theallocated transmit power for an existing device), and the frequencychannel to be used. As an example, the higher the antenna of a device,the greater is the contribution to interference of a signal emitted fromthat device. Accordingly, by counting (performing a weighted sum of) thenumber of devices using ratios of antenna heights among the devices asweights, the risk of harmful interference may be effectively reducedthrough power recalculation or adjustment.

A mechanism that allocates transmit power to secondary systems in atimely manner using the power calculation model described in thissection will now be described in the subsequent sections.

3. Exemplary Configuration of Communication Control Apparatus 3-1.Component Configuration

FIG. 6 is a block diagram illustrating an example of a logicalconfiguration of the communication control apparatus 100 according to anembodiment. Referring to FIG. 6, the communication control apparatus 100includes a communication unit 110, a storage unit 120, and a controlunit 130.

(1) Communication Unit

The communication unit 110 communicates with the wireless communicationapparatus 20 via backhauling of the wireless communication apparatus 20.For example, the communication unit 110 receives an activation requestfrom a wireless communication apparatus 20 that has been activated ormoved to the geographical region managed by the communication controlapparatus 100. The communication unit 110 also receives secondary systeminformation to be discussed later from the relevant wirelesscommunication apparatus 20. Subsequently, after a calculation for thepurpose of power allocation is executed by the control unit 130, thecommunication unit 110 transmits power allocation-related informationbased on the calculation result to the wireless communication apparatus20.

The communication unit 110 may also communicate with the primarytransceiver 10 and the control nodes on the core network 15.Additionally, the communication unit 110 may also communicate with adata server (for example, a GLDB that manages a neighboring region)having the authority to allocate transmit power in a region near thegeographical region managed by the communication control apparatus 100.

(2) Storage Unit

The storage unit 120 uses a storage medium such as a hard disk orsemiconductor memory to store programs and data for the operation of thecommunication control apparatus 100. Data stored by the storage unit 120includes, for example, primary system information collected from theprimary transceiver 10 or control nodes on the core network 15, orstored in advance. The primary system information may include one ormore from among the position of the primary transceiver, the servicearea deployment, protected frequency channels, the minimum receivingsensitivity of the primary terminals, the protection ratio, theshadowing margin, the allowed interference level, an identifier of awireless access technology, and a measured interference level, forexample. The position of the primary transceiver and the service areadeployment may be used when specifying a reference point in the powercalculation model discussed earlier, for example.

In addition, the data stored by the storage unit 120 includes secondarysystem information collected from each of the wireless communicationapparatuses 20. The secondary system information may include one or morefrom among the identifier of the master device, the position, theantenna height, the device type, emission characteristics (for example,the adjacent channel leakage ratio (ACLR)), an identifier of a wirelessaccess technology, and transmit power information (for example, maximumtransmit power and/or desired transmit power).

In addition, the data stored by the storage unit 120 may include powerallocation-related information reported to the wireless communicationapparatus 20. The power allocation-related information may include oneor more from among a list of frequency channels available for use, anominal transmit power (maximum radiated power), an interferenceavoidance margin, an adjustment of the interference avoidance margin,and the period of validity for the information.

In addition, the data stored by the storage unit 120 includes parametersused to calculate the power allocation. The parameters herein mayinclude one or more from among a power allocation calculation period, adetermination threshold to be compared against the number of secondarysystems, a mapping table for deriving the estimated interferencevariation, as well as the number of secondary systems, the aggregatedinterference quantity, and the interference avoidance margin at aprevious base point in time, for example.

(3) Control Unit

The control unit 130 controls overall operation of the communicationcontrol apparatus 100. In the present embodiment, the control unit 130includes a determination unit 132, a calculation unit 134, and asignaling unit 136.

(3-1) Determination Unit

When there is a change in the number of secondary systems within thegeographic region managed by the communication control apparatus 100,the determination unit 132 switches the calculation process for thepurpose of power allocation to be executed by the calculation unit 134,according to a condition depending on the number of secondary systems.As an example, when the changed number of secondary systems falls belowa determination threshold, the determination unit 132 causes thecalculation unit 134 to recalculate the transmit power that should beallocated to the secondary systems according to the margin minimizationmethod in the power calculation model discussed earlier. Also, when thechanged number of secondary systems exceeds a determination threshold,the determination unit 132 causes the calculation unit 134 to adjust thepreviously calculated transmit power. The determination threshold hereinis configured so that the estimated calculation time dependent on thenumber of secondary systems does not exceed an allowed calculation time.

The allowed calculation time may be configured in advance according toany conditions, such as the requirements for the operation andmanagement of the secondary systems, the hardware limitations of thecommunication control apparatus 100, and the rules of the carrier thatoperates and manages the communication control apparatus 100. Inaddition, the determination unit 132 may also configure the allowedcalculation time dynamically in response to a processing condition suchas the load imposed on the processing resources (such as a processor andmemory) of the communication control apparatus 100 or the number ofprocessor cores available for use. The allowed calculation time may alsobe equal to the power allocation calculation period discussed earlier.As an example, in the standard specification of the LTE scheme specifiedby the 3GPP, the scheduling period in an eNodeB isimplementation-dependent, and may be configured to various values, suchas one subframe (=1 ms) or one radio frame (=10 ms). The allowedcalculation time may also be equal to such a scheduling period.

For example, the determination unit 132 tracks changes in the number ofsecondary systems by monitoring activation requests and deactivationrequests received from the wireless communication apparatus 20. N_(WSD)represents the number of secondary systems at a base point in time,while N_(WSD_VAR) represents the variation in the number of secondarysystems since the base point in time. The determination condition forswitching the calculation process in the calculation unit 134 may thenbe expressed as follows.[Math. 12]N _(WSD) +N _(WSD_VAR) >N _(TH)  (12)

When the conditional Expression (12) is satisfied, the determinationunit 132 causes the calculation unit 134 to adjust the previouslycalculated transmit power on the basis of the variation N_(WSD_VAR) inthe number of secondary systems.

In the margin minimization method discussed earlier, provided thatN_(Channel) is the number of frequency channels protected for theprimary system, the number N_(Calc) of individual interference quantitycalculations executed when calculating the aggregated interference forall reference points is expressed by the following expression.[Math. 13]N _(Calc) =N _(Channel) ·N _(WSD) ²  (13)

Furthermore, provided that f_(clock) is the clock frequency of theprocessor, N_(CalcPerClock) is the number of interference quantitiesthat may be calculated in one clock cycle, and D_(TH) is the allowedcalculation time, the maximum number of interference quantities that maybe calculated in the calculation time D_(TH) is equal to the product ofD_(TH), f_(clock), and N_(CalcPerClock). Consequently, the determinationthreshold N_(TH) in the conditional Expression (12) may be derived asfollows.

$\begin{matrix}\left\lbrack {{Math}.\mspace{11mu} 14} \right\rbrack & \; \\{N_{TH} = \sqrt{\frac{D_{TH}f_{Clock}N_{CalcPerClock}}{N_{Channel}}}} & (14)\end{matrix}$

Note that Expression (14) is merely one example. For example, a marginmay also be included in the determination threshold N_(TH).

In a practical example, the base point in time may be the time when thetransmit power was recalculated last by the calculation unit 134. Inthis practical example, provided that the transmit power wasrecalculated last at time T₁, for example, the determination unit 132retains the number of secondary systems at time T₁ as a base valueN_(WSD) with a variation of zero, even if the transmit power is lateradjusted at time T₂. In this case, even if the transmit power is roughlyadjusted several times with the simple technique, adjustment error doesnot accumulate, and the risk of producing harmful interference caused byerror accumulation is avoided.

In another practical example, the base point in time may be theimmediately previous time when the transmit power was recalculated oradjusted. In this practical example, if the transmit power is adjustedat time T₂, the determination unit 132 retains the number of secondarysystems at time T₂ as the base value N_(WSD) with a variation of zero.In this case, since it is sufficient for the determination unit 132 toretain only the number of secondary systems from the most recent andimmediately previous calculation period, the implementation of thecalculation process may be simplified.

Note that the technique of simply adjusting only the interferenceavoidance margin on the basis of the variation in the number ofsecondary systems enables a result to be obtained with a smallcalculation cost, while sacrificing a degree of power allocationoptimization. However, there exist other factors causing the risks ofinterference to vary besides variation in the number of secondarysystems. Accordingly, the determination unit 132 additionally maydetermine whether to cause the calculation unit 134 to recalculate thetransmit power or adjust the previously calculated transmit power,according to an additional determination condition that depends onfactors other than the variation in the number of secondary systems.Herein, the factors governing the additional determination condition maybe at least one from among the reference point, the frequency channel tobe secondarily used, the antenna height of the device, and theinterference level from other systems, for example. For example, whenthe degree of variation for these factors is large, the additionaldetermination condition may be determined to be satisfied, and theinterference avoidance margin may be adjusted.

(3-2) Calculation Unit

The calculation unit 134 calculates the transmit power that should beallocated to one or more secondary systems that secondarily usefrequency channels protected for the primary system. In the presentembodiment, as long as the above determination condition for switchingthe calculation process is not satisfied, the calculation unit 134recalculates (calculates) the transmit power to be allocated to eachsecondary system according to the margin minimization method discussedearlier, for example. In this case, the transmit power of each secondarysystem may be calculated by using the nominal transmit power P_(IB)^(SingleWSD) and the interference avoidance margin IM, as indicated inExpression (2).

When the above determination condition is satisfied, the calculationunit 134 adjusts the interference avoidance margin IM by calculatingonly the margin adjustment dM on the basis of the variation N_(WSD_VAR)in the number of secondary systems, as illustrated in Expression (7) orExpression (9). The calculation unit 134 may calculate the marginadjustment dM by substituting into Expression (7) the variationN_(WSD_VAR) in the number of secondary systems, the variation dI in theinterference quantity estimated on the basis of N_(WSD_VAR), and theaggregated interference quantity I_(Agg,max) at the base point in time,for example. At this point, the calculation unit 134 may also derive theestimated interference variation dI using a mapping table that defines amapping between the variation N_(WSD_VAR) in the number of secondarysystems and the estimated interference variation dI. Also, thecalculation unit 134 may calculate the margin adjustment dM bysubstituting the number N_(WSD) of secondary systems and the variationN_(WSD_VAR) thereof into Expression (9) based on the assumption that thenumber of secondary systems and the aggregated interference quantity areproportional, for example. In either case, calculation costs thatincrease on the order of the square of the number of secondary systemsare not required. Compared to a technique that recalculates the transmitpower for the system as a whole, the calculation of the adjustment dM ofthe interference avoidance margin is completed within a shorter amountof time.

When the number of secondary systems increases, or in other words whenan active wireless communication apparatus 20 newly occurs, thecalculation unit 134 may calculate the nominal transmit power of thesecondary system operated and managed by the new wireless communicationapparatus 20. The nominal transmit power P_(IB) ^(SingleWSD) iscalculated using parameters included in the primary system informationand the secondary system information, in accordance with Expression (1).Depending on the load on the calculation unit 134, the calculation ofthe nominal transmit power may also be entrusted to the secondarysystems. For example, when the load on the calculation unit 134 ishigher than a designated threshold in a certain calculation period, thecalculation unit 134 may entrust the calculation of the nominal transmitpower to the secondary systems. In this case, parameters for calculatingthe nominal transmit power may be signaled to the wireless communicationapparatus 20 that is the master device of a relevant secondary system.

(3-3) Signaling Unit

The signaling unit 136 executes signaling via the communication unit 110with the primary transceiver 10, control nodes on the core network 15,the wireless communication apparatus 20, and other data servers. Forexample, every time the calculation unit 134 recalculates the transmitpower to allocate to each secondary system or adjusts the interferenceavoidance margin, power allocation-related information is reported tothe wireless communication apparatus 20 that is the master device of anactive secondary system.

As an example, according to Expression (2), the transmit power P_(IB)^(WSD) allocated to each secondary system includes the nominal transmitpower P_(IB) ^(SingleWSD) and the interference avoidance margin IM.Whereas the nominal transmit power P_(IB) ^(SingleWSD) is different foreach system, the interference avoidance margin IM is shared in commonfor multiple secondary systems. In the calculation period in which theinterference avoidance margin IM is adjusted, or in other words, in thecalculation period in which the changed number of secondary systemssatisfies the conditional Expression (12), the nominal transmit powerP_(IB) ^(SingleWSD) is not updated, and only the margin adjustment dMindicated in Expression (6) is calculated. In this case, the signalingunit 136 signals only the adjustment dM of the interference avoidancemargin calculated by the calculation unit 134 to existing secondarysystems. Consequently, the signaling overhead is reduced. To the newsecondary systems, the signaling unit 136 signals the adjustment dM ofthe interference avoidance margin, as well as the interference avoidancemargin IM_(Base) and the nominal transmit power P_(IB) ^(SingleWSD) thatwere reported to the existing secondary systems at the previous basepoint in time. The wireless communication apparatus 20 which is themaster device of a secondary system derives the adjusted interferenceavoidance margin IM′ by adding together the interference avoidancemargin IM_(Base) from the base point in time and the margin adjustmentdM. Note that the signaling unit 136 may also signal the adjustedinterference avoidance margin IM′ to both the existing secondary systemsand the new secondary systems. Additionally, the signaling unit 136 mayalso signal the allocated transmit power P_(IB) ^(WSD) to the secondarysystems at some timing.

When the calculation of the nominal transmit power is entrusted to thesecondary system according to the load on the calculation unit 134, thesignaling unit 136 signals parameters for calculating the nominaltransmit power to the new secondary systems. The parameters forcalculating the nominal transmit power may include one or more fromamong the position of the primary transceiver, the list of frequencychannels available for use, the minimum receiving sensitivity of theprimary terminals, the protection ratio, the shadowing margin, and thetotal number of secondary systems (N_(WSD)+N_(WSD_VAR)), for example. Inthis case, the transmit power is calculated by the wirelesscommunication apparatus 20 itself which is the master device of a newsecondary system. The signaling unit 136 may also receive a report ofthe nominal transmit power calculation result from the wirelesscommunication apparatus 20, and store the report in the storage unit120.

In the calculation period in which the transmit power is recalculated,or in other words, in the calculation period in which the changed numberof secondary systems does not satisfy the conditional Expression (12),the nominal transmit power P_(IB) ^(SingleWSD) possibly may be updated.Additionally, the interference avoidance margin IM is also recalculated.The signaling unit 136 signals the recalculated nominal transmit powerP_(IB) ^(SingleWSD) and the interference avoidance margin IM to theexisting secondary systems and the new secondary systems. Theinterference avoidance margin IM reported at this point may be treatedas a base value for later adjustment of the interference avoidancemargin. For existing secondary systems, the signaling of the nominaltransmit power to the existing secondary systems may also be omittedwhen the nominal transmit power is not updated. Additionally, thesignaling to the existing secondary systems may also be conducted bytransmitting a difference only.

A signaling message by which the signaling unit 136 reports powerallocation-related information to the wireless communication apparatus20 may also include an index indicating the type of parameters beingreported. For example, parameter types may be defined as follows.

0: Interference avoidance margin (IM) *may also be used as base valueIM_(Base)

1: Margin adjustment (dM)

2: Interference avoidance margin and margin adjustment (IM, dM)

3: Adjusted margin (IM′=IM_(Base)+dM)

4: Allocated transmit power

The values of the parameter types are not limited to the above example,and may also be other values. By introducing such an index into thesignaling message, it becomes possible for the communication controlsystem 1 to support a variety of signaling variations, and select anoptimal signaling method from the perspective of reducing overhead,reducing the complexity of the implementation, or the like.

As described using FIG. 3, the communication control apparatus 100 mayalso be a data server having the authority to allocate transmit power toone or more secondary systems inside a geographical region 3 a, forexample. However, when allocating transmit power, situations demandingthe consideration of the presence of secondary systems inside aneighboring region 3 b that neighbors the geographical region 3 a mayalso exist. An example of such a situation is when a large number ofsecondary systems or a secondary system that uses a comparatively largetransmit power is operated near the region border. In this case, thesignaling unit 136 may acquire information indicating the number ofsecondary systems that should be considered inside the neighboringregion 3 b from another data server having the authority to allocatetransmit power to secondary systems for the neighboring region 3 b. Atthis point, suppose that N_(WSD_A) is the number of secondary systemsinside the geographical region 3 a, and N_(WSD_B) is the number ofsecondary systems that should be considered, which is acquired fromanother data server. When these values satisfy the following conditionalExpress (15), the assumed calculation time for recalculating thetransmit power by the calculation unit 134 will exceed the allowedcalculation time.[Math. 15]N _(WSD_A) +N _(WSD_B) >N _(TH)  (15)

A comparison of the condition Expression (12) and the conditionalExpression (15) shows that the number of secondary systems N_(WSD_A)means the base value N_(WSD) of the number of secondary systems, whilethe number of secondary systems N_(WSD_B) means the variationN_(WSD_VAR) in secondary systems in the spatial direction. When thedetermination condition of the conditional Expression (15) is satisfied,the determination unit 132 causes the calculation unit 132 to adjust theinterference avoidance margin IM included in the transmit powerpreviously calculated by considering only the geographical region 3 a onthe basis of the variation N_(WSD_B) in the number of secondary systems.Since the number of secondary systems N_(WSD_B) is positive, Expression(7) may be transformed as follows.

$\begin{matrix}\left\lbrack {{Math}.\mspace{11mu} 16} \right\rbrack & \; \\{{{dM} = {10\;{\log_{10}\left( {\frac{N_{{WSD}\;\_\; A} + N_{{WSD}\;\_\; B}}{N_{{WSD}\;\_\; A}} \cdot \frac{Y + 10^{\frac{dI}{10}}}{Y}} \right)}}}{{{where}\mspace{14mu} Y} = 10^{\frac{I_{{Agg},\max}}{10}}}} & (16)\end{matrix}$

In this way, according to the present embodiment, even in a situationdemanding the consideration of the presence of secondary systems insidea neighboring region, it is sufficient for the communication controlapparatus 100 simply to acquire only the number of secondary systemsthat should be considered from a device having authority for therelevant neighboring region. The communication control apparatus 100, byadjusting the interference avoidance margin using the acquired number ofsecondary systems, is able to give communication opportunities tosecondary systems promptly, while also appropriately protecting theprimary system. Note that the signaling unit 136 may also acquire otherparameters, such as the estimated interference variation dI, from thedevice having authority for the neighboring region.

3-2. Modifications

When the variation N_(WSD_VAR) in the number of secondary systems issmall, the margin adjustment dM is also small. In such cases, if themargin adjustment dM is signaled every time the number of secondarysystems changes, the signaling overhead in the communication controlsystem 1 becomes very large, possibly causing a drop in resourceutilization efficiency. Accordingly, this section describes techniquesfor reducing the overhead of power allocation signaling as modificationsof the embodiment discussed above.

(1) First Modification

In the first modification, the margin for reducing signaling overheadproposed in Patent Literature 2 is introduced. The calculation unit 134calculates a transmit power P_(Alloc) ^(WSD) to be allocated to eachsecondary system by using a signaling reduction margin M_(int) inaddition to the nominal transmit power P_(IB) ^(SingleWSD) and theinterference avoidance margin IM, as in the following expression.[Math. 17]P _(Alloc) ^(WSD) =P _(IB) ^(WSD) −M _(Int) ≤P _(IB) ^(SingleWSD) −IM−M_(Int)  (17)

When the number of secondary systems increases, if the total number ofsecondary systems exceeds the determination threshold Nm, thecalculation unit 134 calculates the adjustment dM of the interferenceavoidance margin IM in Expression (17) on the basis of the variationN_(WSD_VAR) in the number of secondary systems. At this point, when thefollowing conditional Expression (18) is satisfied, harmful interferencedoes not occur, even if the secondary systems continually use thealready-allocated transmit power P_(Alloc) ^(WSD). Note that the rightside of the conditional Expression (18) is equal to thealready-allocated transmit power P_(Alloc) ^(WSD).[Math. 18]P _(IB) ^(SingleWSD)−(IM+dM)≥P _(IB) ^(SingleWSD) −IM−M _(Int)  (18)

The condition Expression (18) may be transformed equivalently asfollows.[Math. 19]IM+dM≤IM+M _(Int)dM≤M _(Int)  (19)

Accordingly, when the adjustment dM of the interference avoidance marginfor existing secondary systems falls below the signaling reductionmargin M_(Int) included in the already-allocated transmit power, thesignaling unit 136 does not signal the margin adjustment dM to therelevant existing secondary systems.

Likewise, when the number of secondary systems decreases, if the totalnumber of secondary systems exceeds the determination threshold N_(TH),the calculation unit 134 calculates the adjustment dM of theinterference avoidance margin IM in Expression (17) on the basis of thevariation N_(WSD_VAR) in the number of secondary systems. At this point,when the following conditional Expression (20) is satisfied, thethroughput improvement obtained by adjusting the transmit power of thesecondary systems is small.[Math. 20]|dM|≤M _(TH_Int)  (20)

Herein, M_(TH_Int) is a threshold for reducing signaling overhead thatmay be configured in advance. When the absolute value of the adjustmentdM of the interference avoidance margin for existing secondary systemsfalls below the threshold M_(TH_Int) for reducing signaling overhead,the signaling unit 136 does not signal the margin adjustment dM to therelevant existing secondary systems.

(2) Second Modification

In the second modification, instead of performing strict tracking of thenumber of secondary systems, a type of hysteresis control is introducedto thereby reduce the number of times power allocation is calculated.When adjusting the transmit power, the calculation unit 134 calculatesthe margin adjustment dM by setting the variation N_(WSD_VAR) in thenumber of secondary systems to a greater-than-actual virtual valueN_(WSD_VAR), as in the following expression.

$\begin{matrix}{\mspace{76mu}\left\lbrack {{Math}.\mspace{11mu} 21} \right\rbrack} & \; \\{{dM} = {10\;{\log_{10}\left( {\frac{N_{WSD} + N_{{WSD}\;\_\;{VAR}}^{\prime}}{N_{WSD}} \cdot \frac{Y + {{{sgn}\left( N_{{WDS}\;\_\;{VAR}}^{\prime} \right)} \cdot 10^{\frac{dI}{10}}}}{Y}} \right)}}} & (21)\end{matrix}$

After that, even if the number of secondary systems increases, as longas the total number of secondary systems (N_(WSD)+N_(WSD_VAR)) does notexceed the virtual value (N_(WSD)+N_(WSD_VAR′)), the calculation unit134 does not have to execute adjustment of the interference avoidancemargin. Consequently, signaling to each secondary system is made lessfrequent. The virtual value N_(WSD_VAR′) may be configured statically inadvance, or configured dynamically. For example, the calculation unit134 may retain maximum numbers of secondary systems managed by thecommunication control apparatus 100 at different times as a history ofcommunication, and configure the virtual value N_(WSD_VAR′) so that thevirtual number of secondary systems (N_(WSD)+N_(WSD_VAR′)) becomes equalto the relevant maximum number. Consequently, since a largerinterference avoidance margin is calculated proactively before thenumber of secondary systems increases, transmit power may be allocatedto new secondary systems promptly, without exerting harmful interferenceon the primary system. A period of validity may also be configured forthe virtual value N_(WSD_VAR′). In this case, after the period ofvalidity has passed, the calculation unit 134 may execute adjustment ofthe interference avoidance margin (or recalculation of the transmitpower) irrespectively of the virtual value N_(WSD_VAR′), and signal thepower allocation result to the secondary systems.

Likewise, in the case in which the number of secondary systemsdecreases, as long as the absolute value |N_(WSD_VAR)| of the variationin the number of secondary systems does not exceed a designatedthreshold, the calculation unit 134 does not have to execute adjustmentof the interference avoidance margin.

4. Process Flows

In this section, several examples of the flows of processes that may beexecuted by the communication control apparatus 100 according to theforegoing embodiment will be described.

4-1. Power Distribution Process (1) First Example

FIG. 7A is a flowchart illustrating a first example of the flow of apower distribution process according to an embodiment. In the firstexample, the time at which the transmit power was recalculated last bythe calculation unit 134 is treated as the base point in time for thevariation in the number of secondary systems.

Referring to FIG. 7A, first, the determination unit 132 stands by achange in the number of secondary systems (step S110). Subsequently,when the number of secondary systems changes, the process proceeds tostep S115.

Next, the determination unit 132 determines whether the changed numberof secondary systems (N_(WSD)+N_(WSD_VAR)) exceeds the determinationthreshold N_(TH) (step S115). If the changed number of secondary systemsdoes not exceed the determination threshold, the process proceeds tostep S120. On the other hand, if the changed number of secondary systemsexceeds the determination threshold, the process proceeds to step S140.

In step S120, the calculation unit 134 recalculates the nominal transmitpower and the interference avoidance margin according to the powerdistribution method described in Patent Literature 1 or the marginminimization method described in Non-Patent Literature 2 (step S120).Subsequently, the signaling unit 136 reports the recalculated nominaltransmit power and interference avoidance margin to the wirelesscommunication apparatus 20 which is the master device of each of theexisting secondary systems and the new secondary systems (step S125).Also, the calculation unit 134 updates the base value N_(WSD) of thenumber of secondary systems and the maximum aggregated interferencequantity I_(Agg,max) at the base point in time to the most recent values(step S130).

In step S140, the calculation unit 134 adjusts the interferenceavoidance margin IM by calculating the adjustment dM of the interferenceavoidance margin on the basis of the variation N_(WSD_VAR) in the numberof secondary systems (step S140). Subsequently, the signaling unit 136reports the margin adjustment dM calculated by the calculation unit 134to the wireless communication apparatus 20 which is the master device ofeach of the existing secondary systems (step S145).

Furthermore, the calculation unit 134 determines whether to calculatethe nominal transmit power for the new secondary systems, depending onthe load at the time (step S150). For example, when the load on thecalculation unit 134 is relatively high, the calculation of the nominaltransmit power is entrusted to the secondary systems. In this case, thesignaling unit 136 reports parameters for calculating the nominaltransmit power, the interference avoidance margin and the adjustmentthereof to the wireless communication apparatus 20 which is the masterdevice of each of the new secondary systems (step S155). On the otherhand, when the load on the calculation unit 134 is relatively low, thecalculation of the nominal transmit power is not entrusted to thesecondary systems. In this case, the calculation unit 134 calculates thenominal transmit power for the new secondary systems (step S160).Subsequently, the signaling unit 136 reports the nominal transmit power,the interference avoidance margin and the adjustment thereof to thewireless communication apparatus 20 which is the master device of eachof the new secondary systems (step S165).

After that, during the period until the next calculation timing arrives,variation in the number of secondary systems is monitored by thedetermination unit 132, and the process returns to step S110 (stepS180).

(2) Second Example

FIG. 7B is a flowchart illustrating a second example of the flow of apower distribution process according to an embodiment. In the secondexample, the immediately previous time at which the transmit power wasrecalculated or adjusted is treated as the base point in time for thevariation in the number of secondary systems. Also, the determinationthreshold N_(TH) is configured dynamically. Note that the configurationis not limited to such an example, and the determination thresholdN_(TH) may be configured dynamically in the first example, or thedetermination threshold N_(TH) may be configured statically in advancein the second example.

Referring to FIG. 7B, first, the determination unit 132 configures thedetermination threshold N_(TH) according to a processing condition suchas the load imposed on the processing resources of the communicationcontrol apparatus 100 or the number of processor cores available for use(step S105). Also, the determination unit 132 stands by for a change inthe number of secondary systems (step S110). Subsequently, when thenumber of secondary systems changes, the process proceeds to step S115.

Next, the determination unit 132 determines whether the changed numberof secondary systems (N_(WSD)+N_(WSD_VAR)) exceeds the determinationthreshold N_(TH) (step S115). If the changed number of secondary systemsdoes not exceed the determination threshold, the process proceeds tostep S120. On the other hand, if the changed number of secondary systemsexceeds the determination threshold, the process proceeds to step S140.

In step S120, the calculation unit 134 recalculates the nominal transmitpower and the interference avoidance margin according to the powerdistribution method described in Patent Literature 1 or the marginminimization method described in Non-Patent Literature 2 (step S120).Subsequently, the signaling unit 136 reports the recalculated nominaltransmit power and interference avoidance margin to the wirelesscommunication apparatus 20 which is the master device of each of theexisting secondary systems and the new secondary systems (step S125).

In step S140, the calculation unit 134 adjusts the interferenceavoidance margin IM by calculating the adjustment dM of the interferenceavoidance margin on the basis of the variation N_(WSD_VAR) in the numberof secondary systems (step S140). Subsequently, the signaling unit 136reports the margin adjustment dM calculated by the calculation unit 134to the wireless communication apparatus 20 which is the master device ofeach of the existing secondary systems (step S145).

Furthermore, the calculation unit 134 determines whether to calculatethe nominal transmit power for the new secondary systems, depending onthe load at the time (step S150). For example, when the load on thecalculation unit 134 is relatively high, the signaling unit 136 reportsparameters for calculating the nominal transmit power, the interferenceavoidance margin and the adjustment thereof to the wirelesscommunication apparatus 20 which is the master device of each of the newsecondary systems (step S155). On the other hand, when the load on thecalculation unit 134 is relatively low, the calculation unit 134calculates the nominal transmit power for the new secondary systems(step S160). Subsequently, the signaling unit 136 reports the nominaltransmit power, the interference avoidance margin and the adjustmentthereof to the wireless communication apparatus 20 which is the masterdevice of each of the new secondary systems (step S165).

After that, the calculation unit 132 updates the base value Nwso of thenumber of secondary systems and the maximum aggregated interferencequantity I_(Agg,max) at the base point in time to the most recent values(step S175). Subsequently, during the period until the next calculationtiming arrives, variation in the number of secondary systems ismonitored by the determination unit 132, and the process returns to stepS105 (step S180).

(3) Third Example

FIG. 7C is a flowchart illustrating a third example of the flow of apower distribution process according to an embodiment. In the thirdexample, the time at which the transmit power was recalculated last bythe calculation unit 334 is treated as the base point in time for thevariation in the number of secondary systems, similarly to the firstexample. In the third example, the technique of reducing signalingoverhead described as the first modification in the previous section isintroduced.

Referring to FIG. 7C, first, the determination unit 132 stands by achange in the number of secondary systems (step S110). Subsequently,when the number of secondary systems changes, the process proceeds tostep S115.

Next, the determination unit 132 determines whether the changed numberof secondary systems exceeds the determination threshold (step S115). Ifthe changed number of secondary systems does not exceed thedetermination threshold, the process proceeds to step S121. On the otherhand, if the changed number of secondary systems exceeds thedetermination threshold, the process proceeds to step S140.

In step S121, the calculation unit 134 recalculates the nominal transmitpower and the interference avoidance margin according to the powerdistribution method described in Patent Literature 1 or the marginminimization method described in Non-Patent Literature 2. Forrecalculation, the signaling reduction margin M_(Int) is also introduced(step S121). Subsequently, the signaling unit 136 reports therecalculated nominal transmit power and margin to the wirelesscommunication apparatus 20 which is the master device of each of theexisting secondary systems and the new secondary systems (step S126).Also, the calculation unit 132 updates the base value N_(WSD) of thenumber of secondary systems and the maximum aggregated interferencequantity I_(Agg,max) at the base point in time to the most recent values(step S130).

In step S140, the calculation unit 134 adjusts the interferenceavoidance margin by calculating the adjustment of the interferenceavoidance margin on the basis of the variation in the number ofsecondary systems (step S140). Subsequently, the signaling unit 136determines whether the margin adjustment calculated by the calculationunit 134 should be signaled (step S144). For example, when the marginadjustment dM does not satisfy the condition Expression (19) or theconditional Expression (20) discussed earlier, the signaling unit 136may determine that the margin adjustment dM should be signaled. If it isdetermined that the margin adjustment dM should be signaled, thesignaling unit 136 reports the margin adjustment calculated by thecalculation unit 134 to the wireless communication apparatus 20 which isthe master device of each of the existing secondary systems (step S145).

Furthermore, the calculation unit 134 calculates the nominal transmitpower for the new secondary systems (step S160). Subsequently, thesignaling unit 136 reports the nominal transmit power, the interferenceavoidance margin, the margin adjustment, and the signaling reductionmargin to the wireless communication apparatus 20 which is the masterdevice of each of the new secondary systems (step S166).

After that, during the period until the next calculation timing arrives,variation in the number of secondary systems is monitored by thedetermination unit 132, and the process returns to step S110 (stepS180).

(4) Fourth Example

FIG. 7D is a flowchart illustrating a fourth example of the flow of apower distribution process according to an embodiment. In the fourthexample, the technique of reducing signaling overhead described as thesecond modification in the previous section is introduced.

Referring to FIG. 7D, first, the determination unit 132 stands by achange in the number of secondary systems (step S110). Subsequently,when the number of secondary systems changes, the process proceeds tostep S115.

Next, the determination unit 132 determines whether the changed numberof secondary systems exceeds the determination threshold (step S115). Ifthe changed number of secondary systems does not exceed thedetermination threshold, the process proceeds to step S120. On the otherhand, if the changed number of secondary systems exceeds thedetermination threshold, the process proceeds to step S135.

In step S120, the calculation unit 134 recalculates the nominal transmitpower and the interference avoidance margin according to the powerdistribution method described in Patent Literature 1 or the marginminimization method described in Non-Patent Literature 2 (step S120).Subsequently, the signaling unit 136 reports the recalculated nominaltransmit power and interference avoidance margin to the wirelesscommunication apparatus 20 which is the master device of each of theexisting secondary systems and the new secondary systems (step S125).Also, the calculation unit 132 updates the base value N_(WSD) of thenumber of secondary systems and the maximum aggregated interferencequantity I_(Agg,max) at the base point in time to the most recent values(step S130).

In step S135, the determination unit 132 additionally compares theabsolute value of the variation in the number of secondary systems to athreshold value (step S135). The threshold value at this point may bethe virtual variation N_(WSD_VAR′). In addition, different thresholdvalues for the case of an increase and the case of a decrease may beused. If the absolute value of the variation in the number of secondarysystems exceeds the threshold value, the calculation unit 134 adjuststhe interference avoidance margin by calculating the adjustment of theinterference avoidance margin on the basis of the virtual variation inthe number of secondary systems (step S139). Subsequently, the signalingunit 136 reports the margin adjustment calculated by the calculationunit 134 to the wireless communication apparatus 20 which is the masterdevice of each of the existing secondary systems (step S145). If theabsolute value of the variation in the number of secondary systems doesnot exceed the threshold value, these steps S140 and S145 are skipped.

Furthermore, the calculation unit 134 calculates the nominal transmitpower for the new secondary systems (step S160). Subsequently, thesignaling unit 136 reports the nominal transmit power, the interferenceavoidance margin, and the margin adjustment to the wirelesscommunication apparatus 20 which is the master device of each of the newsecondary systems (step S165).

After that, during the period until the next calculation timing arrives,variation in the number of secondary systems is monitored by thedetermination unit 132, and the process returns to step S110 (stepS180).

4-2. Margin Adjustment Process

FIG. 8 is a flowchart illustrating an example of the flow of a marginadjustment process (corresponding to step S140) which may be executedduring the power distribution process illustrated in FIGS. 7A to 7C.

Referring to FIG. 8, first, the calculation unit 134 derives theestimated interference variation dI on the basis of the variationN_(WSD_VAR) in the number of secondary systems (step S141). Next, thecalculation unit 134 acquires the aggregated interference quantityI_(Agg,max) at the base point in time from the storage unit 120 (stepS142). Subsequently, the calculation unit 134 computes the marginadjustment dM by substituting the variation N_(WSD_VAR) in the number ofsecondary systems, the estimated interference variation dI, and theaggregated interference quantity I_(Agg,max) into Expression (7) (stepS143).

Note that when Expression (9) is used based on the assumption that thenumber of secondary systems and the aggregated interference quantity areproportional, the derivation of the estimated interference variation dIand the substitution of dI into the formula may also be omitted.

4-3. Signaling Sequence

FIGS. 9A and 9B illustrate an example of a signaling sequence in thecommunication control system 1 according to an embodiment. In thesequence of FIG. 9A, the communication control apparatus 100, a wirelesscommunication apparatus 20 a which is the master device of an existingsecondary system, and a wireless communication apparatus 20 h which isthe master device of a new secondary system participate. Note that onlythe wireless communication apparatuses 20 a and 20 h are illustratedherein for the sake of simplicity, but in actual practice, thecommunication control system 1 is assumed to include more wirelesscommunication apparatuses 20.

Referring to FIG. 9A, first, the wireless communication apparatus 20 htransmits an activation request to the communication control apparatus100 (step S10). Upon receiving the activation request from the wirelesscommunication apparatus 20 h, the communication control apparatus 100counts up the number of secondary systems.

When a periodic calculation timing arrives, the communication controlapparatus 100 executes the power distribution process described usingFIGS. 7A to 7D (step S15). As a result, the transmit power that shouldbe allocated to the secondary system is recalculated, or the previouslycalculated transmit power is adjusted on the basis of the variation inthe number of secondary systems.

The communication control apparatus 100 indicates that activation isallowed, and also signals the power allocation result to the wirelesscommunication apparatus 20 h (step S20). In addition, the communicationcontrol apparatus 100 signals the power allocation result or the marginadjustment result to the wireless communication apparatus 20 a (stepS20).

The wireless communication apparatus 20 h calculates the transmit powerallocated to the new secondary system by using the power allocationresult indicated by the communication control apparatus 100 (step S30).Additionally, the wireless communication apparatus 20 h may report thecalculated allocated transmit power to the communication controlapparatus 100 (step S35).

The wireless communication apparatus 20 a calculates the recalculated oradjusted allocated transmit power by using the power allocation resultof the margin adjustment result indicated by the communication controlapparatus 100 (step S40). Additionally, the wireless communicationapparatus 20 a may report the calculated allocated transmit power to thecommunication control apparatus 100 (step S45).

Referring to FIG. 9B, there are illustrated a data server having theauthority to allocate transmit power for a neighboring region 3 bneighboring the geographical region 3 a that includes the communicationcontrol apparatus 100, the wireless communication apparatus 20 a, andthe wireless communication apparatus 20 h, and a wireless communicationapparatus inside the neighboring region 3 b.

In a situation demanding the consideration of the presence of thesecondary system inside the neighboring region 3 b, the number ofsecondary systems that should be considered is signaled to thecommunication control apparatus 100 from the data server havingauthority for the neighboring region 3 b (step S50). The number ofsecondary systems signaled at this point corresponds to the parameterN_(WSD_B) in Expression (15) and Expression (16) discussed earlier, andis treated as a variation in the number of secondary systems.

The communication control apparatus 100 executes the power distributionprocess using the number _(WSD_A) of secondary systems inside thegeographical region 3 a and the number N_(WSD_B) of secondary systemsthat should be considered inside the neighboring region 3 b (step S55).As a result, the transmit power that should be allocated to thesecondary system is recalculated, or the previously calculated transmitpower is adjusted on the basis of N_(WSD_B).

The communication control apparatus 100 signals the power allocationresult or the margin adjustment result to the wireless communicationapparatus 20 a and the wireless communication apparatus 20 h (steps S60,S65).

The wireless communication apparatus 20 h calculates the recalculated oradjusted allocated transmit power by using the power allocation resultof the margin adjustment result indicated by the communication controlapparatus 100 (step S70). Additionally, the wireless communicationapparatus 20 h may report the calculated allocated transmit power to thecommunication control apparatus 100 (step S75).

Similarly, the wireless communication apparatus 20 a calculates therecalculated or adjusted allocated transmit power by using the powerallocation result of the margin adjustment result indicated by thecommunication control apparatus 100 (step S80). Additionally, thewireless communication apparatus 20 a may report the calculatedallocated transmit power to the communication control apparatus 100(step S85).

5. Exemplary Configuration of Wireless Communication Apparatus

FIG. 10 is a block diagram illustrating an example of a logicalconfiguration of the wireless communication apparatus 20 according to anembodiment. Referring to FIG. 10, the wireless communication apparatus20 includes a wireless communication unit 210, a network communicationunit 220, a storage unit 230, and a communication control unit 240.

(1) Wireless Communication Section

The wireless communication unit 210 executes wireless communication withterminal devices positioned nearby (slave devices of the secondarysystem) using transmit power allocated by the communication controlapparatus 100. For example, the wireless communication unit 210transmits a beacon signal on one of the frequency channels available foruse as indicated by the communication control apparatus 100. Uponsensing the beacon signal, a slave device exchanges parameters for theoperation and management of the secondary system with the wirelesscommunication apparatus 20, and initiates wireless communication. Theparameters exchanged at this point may include parameters forcontrolling the transmit power of the slave device (for example, a valueof transmit power).

(2) Network Communication Unit

The network communication unit 220 establishes backhauling between thewireless communication apparatus 20 and the communication controlapparatus 100. Subsequently, the network communication unit 220 receivesvarious signaling messages transmitted from the communication controlapparatus 100 over backhauling. In addition, the network communicationunit 220 transmits secondary system information about the secondarysystem operated and managed by the wireless communication apparatus 20to the communication control apparatus 100. Note that when thebackhauling is a wireless link, the network communication unit 220 maybe omitted from the configuration of the wireless communicationapparatus 20.

(3) Storage Unit

The storage unit 230 uses a storage medium such as a hard disk orsemiconductor memory to store programs and data for the operation of thewireless communication apparatus 20. Data stored by the storage unit 230may include secondary system information about the secondary systemoperated and managed by the wireless communication apparatus 20, powerallocation-related information indicated by the communication controlapparatus 100, and slave device information, for example.

(4) Communication Control Unit

The communication control unit 240 controls communication executed bythe wireless communication apparatus 20. For example, when the wirelesscommunication apparatus 20 starts the operation and management of thesecondary system (or returns from sleep mode), the communication controlunit 240 transmits an activation request to the communication controlapparatus 100 via backhauling. Subsequently, if power allocation-relatedinformation is received from the communication control apparatus 100,the operating frequency and transmit power for the wirelesscommunication unit 210 are configured in accordance with the transmitpower allocation by the communication control apparatus 100.

Consequently, wireless communication becomes possible between thewireless communication apparatus 20 which acts as the master device, andone or more slave devices. The maximum transmit power usable by thewireless communication unit 210 may be calculated by subtracting theinterference avoidance margin (and if necessary, the signaling reductionmargin) from the nominal transmit power indicated by the communicationcontrol apparatus 100. If a signaling message indicating an adjustmentof the interference avoidance margin is received from the communicationcontrol apparatus 100, the communication control unit 240 updates theconfiguration of the transmit power in the wireless communication unit210 by adding the margin adjustment to the margin included in thealready-configured transmit power. When the operation and management ofthe secondary system is stopped (or transitioned to sleep mode), thecommunication control unit 240 transmits a deactivation request to thecommunication control apparatus 100 via backhauling. Consequently, thecommunication control apparatus 100 is able to recognize a decrease insecondary systems.

6. Another Example of System Model

FIG. 1 illustrates a system model in which a communication controlapparatus 100 that may correspond to a GLDB is deployed in thecommunication control system 1, and in which the communication controlapparatus 100 executes power calculation and signaling with secondarysystems. However, such a system model is merely one example. Forexample, the functions of the communication control apparatus 100discussed above may also be realized by two or more hierarchicallyseparated entities.

FIG. 11 is an explanatory diagram for describing another example of asystem model. Referring to FIG. 11, the communication control system 2includes a GLDB 102, one or more white space databases (WSDBs) 104 a,104 b, and so on, one or more master WSDs 20 a, 20 b, and so on, and oneor more slave WSDs. The GLDB 102 includes, from among the functions ofthe communication control apparatus 100 discussed earlier, thecalculation function primarily used for power allocation and thefunction of switching between power recalculation and adjustmentaccording to the determination condition discussed earlier. In addition,the GLDB 102 also includes a function of communicating with otherentities, which may include the WSDBs 104 a, 104 b, and so on(hereinafter collectively termed the WSDB 104). When there is a changein the number of secondary systems inside the geographical regionmanaged by the GLDB 102 itself, the GLDB 102 recalculates the allocatedtransmit power for the secondary systems, or alternatively, adjusts theinterference avoidance margin on the basis of the variation in thenumber of secondary systems.

The WSDB 104 includes a function of acquiring information indicating thetransmit power calculation result from the GLDB 102, and signalingparameters for specifying the allocated transmit power of each secondarysystem to the master device of the relevant secondary system. Inaddition, the WSDB 104 also includes a function of communicating withother entities that may include the GLDB 102, and a function ofcommunicating with the master WSD 20. The WSDB 104 may also receiveinformation indicating the transmit power calculation result from theGLDB 102 directly, or acquire such information via another WSDB. As anexample, the GLDB 102 may be a server administered by an official orpublic organization, whereas the WSDB may be server administered by afor-profit or non-profit enterprise.

The GLDB 102 periodically (or non-periodically) calculates(recalculates/adjusts) the transmit power that should be allocated tothe secondary systems on the basis of primary system information andsecondary system information reported by the WSDB 104. Subsequently, theGLDB 102 transmits the power allocation-related information discussedearlier that indicates the calculation result to the WSDB 104. The powerallocation-related information at least includes a parameter specifyingthe calculated interference avoidance margin. The type of the parametermay be an arbitrary type, such as those described with regards to thesignaling unit 136 of the communication control apparatus 100.

In the first example, the power allocation-related information isassociated with individual secondary systems (or master WSDs), and mayinclude a system ID or a device ID, for example. In this case, the WSDB104 may signal, in response to a request from the master WSD 20,information corresponding to the ID of the request source to the masterWSD 20. In the second example, the power allocation-related informationis associated with location (and device attributes such as antennaheight). For example, the geographical region managed by the GLDB 102 issegmented into a grid, and identification information is assigned toindividual segments. Subsequently, the power allocation-relatedinformation is provided to the WSDB 104 in the form of a table mappingpairs of a segment and a device attribute (antenna height, for example)with a margin value. In this case, the WSDB 104 may signal, in responseto a request from the master WSD 20, the margin value mapped to the pairof the segment where the requesting device is positioned and theattribute. In either example, the WSDB 104 may also signal the nominaltransmit power and the interference avoidance margin to each master WSD20. Alternatively, on the basis of the power allocation-relatedinformation, the WSDB 104 may also calculate the allocated transmitpower of individual master WSDs 20 from the nominal transmit power andthe interference avoidance margin (base value and adjustment), andsignal parameters for specifying the calculated allocated transmit powerto individual master WSDs 20. Additionally, the WSDB 104 may also signalto the master WSD 20 parameters enabling the master WSD 20 to calculatethe nominal transmit power.

The master WSD 20 corresponds to the wireless communication apparatus 20described using FIG. 10. The master WSD 20 includes a function ofcommunicating with the WSDB 104 having power allocation-relatedinformation that specifies the allocated transmit power for thesecondary system that the master WSD 20 itself operates and manages. Themaster WSD 20 receives the signaling of parameters for specifying theallocated transmit power from the connected WSDB 104, and controlswireless communication between the master WSD 20 and one or more slaveWSDs in accordance with the allocated transmit power specified using thereceived parameters.

7. Application Examples

The technology of the present disclosure is applicable to variousproducts. For example, the communication control apparatuses 100, 102,and 104 may be realized as any type of data server such as a towerserver, a rack server, and a blade server. The communication controlapparatuses 100, 102, and 104 may be a control module (such as anintegrated circuit module fabricated on a single die, and a card or ablade that is inserted into a slot of a blade server) mounted on aserver.

As another example, the wireless communication apparatus 20 may also berealized as an evolved Node B (eNB) of any type, such as a macro eNB, apico eNB, or a home eNB. Conversely, the wireless communicationapparatus 20 may also be realized as another type of base station, suchas a NodeB or a base transceiver station (BTS).

For example, the wireless communication apparatus 20 may be realized asa mobile terminal such as a smartphone, a tablet personal computer (PC),a notebook PC, a portable game terminal, a portable/dongle type mobilerouter, and a digital camera, or an in-vehicle terminal such as a carnavigation apparatus. The wireless communication apparatus 20 may alsobe realized as a terminal (that is also referred to as a machine typecommunication (MTC) terminal) that performs machine-to-machine (M2M)communication. Furthermore, the wireless communication apparatus 20 maybe a radio communication module (such as an integrated circuit modulefabricated on a single die) mounted on each of the terminals.

7-1. Application Example Related to Networking Control Node

FIG. 12 is a block diagram illustrating an example of the schematicconfiguration of a GLDB 700 to which the technology of the presentdisclosure may be applied. The GLDB 700 includes a processor 701, amemory 702, a storage 703, a network interface 704, and a bus 706.

The processor 701 may be, for example, a central processing unit (CPU)or a digital signal processor (DSP), and controls functions of theserver 700. The memory 702 includes a random access memory (RAM) and aread only memory (ROM), and stores a program that is executed by theprocessor 701 and data. The storage 703 may include a storage mediumsuch as a semiconductor memory and a hard disk.

The network interface 704 is a wired communication interface forconnecting the GLDB 700 to a wired communication network 705. The wiredcommunication network 705 may be a core network such as an evolvedpacket core (EPC), or a packet data network (PDN) such as the Internet.

The bus 706 connects the processor 701, the memory 702, the storage 703,and the network interface 704 to each other. The bus 706 may include twoor more buses (such as a high speed bus and a low speed bus) each ofwhich has different speed.

In the GLDB 700 illustrated in FIG. 12, the control unit 130 describedusing FIG. 6 may be implemented in the processor 701. For example, theprocessor 701 functions as the determination unit 132, the calculationunit 134, and the signaling unit 136, and thereby is able to trackvariation in the number of secondary systems within the geographicalregion managed by the GLDB 700 to allocate transmit power to eachsecondary system promptly while also preventing harmful interference onthe primary system.

7-2. Application Examples Related to Base Station

FIG. 13 is a block diagram illustrating an example of the schematicconfiguration of an eNB to which the technology of the presentdisclosure may be applied. An eNB 800 includes one or more antennas 810and a base station apparatus 820. Each antenna 810 and the base stationapparatus 820 may be connected to each other via an RF cable.

Each of the antennas 810 includes a single or multiple antenna elements(such as multiple antenna elements included in an MIMO antenna), and isused for the base station apparatus 820 to transmit and receive radiosignals. The eNB 800 may include the multiple antennas 810, asillustrated in FIG. 13. For example, the multiple antennas 810 may becompatible with multiple frequency bands used by the eNB 800,respectively. Note that FIG. 13 illustrates the example in which the eNB800 includes the multiple antennas 810, but the eNB 800 may also includea single antenna 810.

The base station apparatus 820 includes a controller 821, a memory 822,a network interface 823, and a radio communication interface 825.

The controller 821 may be, for example, a CPU or a DSP, and operatesvarious functions of a higher layer of the base station apparatus 820.For example, the controller 821 generates a data packet from data insignals processed by the radio communication interface 825, andtransfers the generated packet via the network interface 823. Thecontroller 821 may bundle data from multiple base band processors togenerate the bundled packet and transfer the generated bundled packet.The controller 821 may have logical functions of performing control suchas radio resource control, radio bearer control, mobility management,admission control, and scheduling. The control may be performed incorporation with an eNB or a core network node in the vicinity. Thememory 822 includes a RAM and a ROM, and stores a program that isexecuted by the controller 821, and various types of control data (suchas a terminal list, transmission power data, and scheduling data).

The network interface 823 is a communication interface for connectingthe base station apparatus 820 to the wired communication network 705.The controller 891 may communicate with the GLDB 700 via the networkinterface 823.

The radio communication interface 825 supports any cellularcommunication scheme such as long term evolution (LTE) and LTE-Advanced,and provides radio connection to a terminal (a slave device) positionedin a cell of the eNB 800 via the antenna 810. The radio communicationinterface 825 may typically include, for example, a baseband (BB)processor 826 and an RF circuit 827. The BB processor 826 may perform,for example, encoding/decoding, modulating/demodulating, andmultiplexing/demultiplexing, and performs various types of signalprocessing of layers (such as L1, medium access control (MAC), radiolink control (RLC), and a packet data convergence protocol (PDCP)). TheBB processor 826 may have a part or all of the above-described logicalfunctions instead of the controller 821. The BB processor 826 may be amemory that stores a communication control program, or a module thatincludes a processor and a related circuit configured to execute theprogram. Updating the program may allow the functions of the BBprocessor 826 to be changed. The module may be a card or a blade that isinserted into a slot of the base station apparatus 820. Alternatively,the module may also be a chip that is mounted on the card or the blade.Meanwhile, the RF circuit 827 may include, for example, a mixer, afilter, and an amplifier, and transmits and receives radio signals viathe antenna 810.

The radio communication interface 825 may include the multiple BBprocessors 826, as illustrated in FIG. 13. For example, the multiple BBprocessors 826 may be compatible with multiple frequency bands used bythe eNB 800. The radio communication interface 825 may include themultiple RF circuits 827, as illustrated in FIG. 13. For example, themultiple RF circuits 827 may be compatible with multiple antennaelements, respectively. Note that FIG. 13 illustrates the example inwhich the radio communication interface 825 includes the multiple BBprocessors 826 and the multiple RF circuits 827, but the radiocommunication interface 825 may also include a single BB processor 826or a single RF circuit 827.

In the eNB 800 illustrated in FIG. 13, the communication control unit240 described using FIG. 10 may be implemented in the radiocommunication interface 825. Also, at least some of the functions mayalso be implemented in the controller 821. For example, by executingwireless communication with slave devices using transmit power allocatedby the communication control apparatus 100, the eNB 800 is able toinitiate the management and operation of a secondary system promptlywhile also preventing harmful interference on the primary system.

Second Application Example

FIG. 14 is a block diagram illustrating an example of the schematicconfiguration of a smartphone 900 to which the technology of the presentdisclosure may be applied. The smartphone 900 includes a processor 901,a memory 902, a storage 903, an external connection interface 904, acamera 906, a sensor 907, a microphone 908, an input device 909, adisplay device 910, a speaker 911, a radio communication interface 912,one or more antenna switches 915, one or more antennas 916, a bus 917, abattery 918, and an auxiliary controller 919.

The processor 901 may be, for example, a CPU or a system on chip (SoC),and controls functions of an application layer and another layer of thesmartphone 900. The memory 902 includes RAM and ROM, and stores aprogram that is executed by the processor 901, and data. The storage 903may include a storage medium such as a semiconductor memory and a harddisk. The external connection interface 904 is an interface forconnecting an external device such as a memory card and a universalserial bus (USB) device to the smartphone 900.

The camera 906 includes an image sensor such as a charge coupled device(CCD) and a complementary metal oxide semiconductor (CMOS), andgenerates a captured image. The sensor 907 may include a group ofsensors such as a measurement sensor, a gyro sensor, a geomagneticsensor, and an acceleration sensor. The microphone 908 converts soundsthat are input to the smartphone 900 to audio signals. The input device909 includes, for example, a touch sensor configured to detect touchonto a screen of the display device 910, a keypad, a keyboard, a button,or a switch, and receives an operation or an information input from auser. The display device 910 includes a screen such as a liquid crystaldisplay (LCD) and an organic light-emitting diode (OLED) display, anddisplays an output image of the smartphone 900. The speaker 911 convertsaudio signals that are output from the smartphone 900 to sounds.

The radio communication interface 912 supports any cellularcommunication scheme such as LTE and LTE-A, and performs radiocommunication. The radio communication interface 912 may typicallyinclude, for example, a BB processor 913 and an RF circuit 914. The BBprocessor 913 may perform, for example, encoding/decoding,modulating/demodulating, and multiplexing/demultiplexing, and performsvarious types of signal processing for radio communication. Meanwhile,the RF circuit 914 may include, for example, a mixer, a filter, and anamplifier, and transmits and receives radio signals via the antenna 916.The radio communication interface 912 may also be a one chip module thathas the BB processor 913 and the RF circuit 914 integrated thereon. Theradio communication interface 912 may include the multiple BB processors913 and the multiple RF circuits 914, as illustrated in FIG. 14. Notethat FIG. 14 illustrates the example in which the radio communicationinterface 912 includes the multiple BB processors 913 and the multipleRF circuits 914, but the radio communication interface 912 may alsoinclude a single BB processor 913 or a single RF circuit 914.

Furthermore, in addition to a cellular communication scheme, the radiocommunication interface 912 may support another type of radiocommunication scheme such as a short-distance wireless communicationscheme, a near field communication scheme, and a radio local areanetwork (LAN) scheme. In that case, the radio communication interface912 may include the BB processor 913 and the RF circuit 914 for eachradio communication scheme.

Each of the antenna switches 915 switches connection destinations of theantennas 916 among multiple circuits (such as circuits for differentradio communication schemes) included in the radio communicationinterface 912.

Each of the antennas 916 includes a single or multiple antenna elements(such as multiple antenna elements included in an MIMO antenna), and isused for the radio communication interface 912 to transmit and receiveradio signals. The smartphone 900 may include the multiple antennas 916,as illustrated in FIG. 14. Note that FIG. 14 illustrates the example inwhich the smartphone 900 includes the multiple antennas 916, but thesmartphone 900 may also include a single antenna 916.

Furthermore, the smartphone 900 may include the antenna 916 for eachradio communication scheme. In that case, the antenna switches 915 maybe omitted from the configuration of the smartphone 900.

The bus 917 connects the processor 901, the memory 902, the storage 903,the external connection interface 904, the camera 906, the sensor 907,the microphone 908, the input device 909, the display device 910, thespeaker 911, the radio communication interface 912, and the auxiliarycontroller 919 to each other. The battery 918 supplies power to blocksof the smartphone 900 illustrated in FIG. 14 via feeder lines, which arepartially shown as dashed lines in the figure. The auxiliary controller919 operates a minimum necessary function of the smartphone 900, forexample, in a sleep mode.

The smartphone 900 illustrated in FIG. 14 may also operate as the masterdevice of a secondary system. In this case, the communication controlunit 240 described using FIG. 10 may be implemented in the radiocommunication interface 912. Also, at least some of these functions mayalso be implemented in the processor 901 or the auxiliary controller919. For example, by executing wireless communication with slave devicesusing transmit power allocated by the communication control apparatus100, the smartphone 900 is able to initiate the management and operationof a secondary system promptly while also preventing harmfulinterference on the primary system. Additionally, the smartphone 900 mayalso operate as a slave device of a secondary system.

Third Application Example

FIG. 15 is a block diagram illustrating an example of the schematicconfiguration of a car navigation apparatus 920 to which the technologyof the present disclosure may be applied. The car navigation apparatus920 includes a processor 921, a memory 922, a global positioning system(GPS) module 924, a sensor 925, a data interface 926, a content player927, a storage medium interface 928, an input device 929, a displaydevice 930, a speaker 931, a radio communication interface 933, one ormore antenna switches 936, one or more antennas 937, and a battery 938.

The processor 921 may be, for example, a CPU or a SoC, and controls anavigation function and another function of the car navigation apparatus920. The memory 922 includes a RAM and a ROM, and stores a program thatis executed by the processor 921, and data.

The GPS module 924 uses GPS signals received from a GPS satellite tomeasure a position (such as latitude, longitude, and altitude) of thecar navigation apparatus 920. The sensor 925 may include a group ofsensors such as a gyro sensor, a geomagnetic sensor, and an air pressuresensor. The data interface 926 is connected to, for example, anin-vehicle network 941 via a terminal that is not shown, and acquiresdata generated by the vehicle, such as vehicle speed data.

The content player 927 reproduces content stored in a storage medium(such as a CD and a DVD) that is inserted into the storage mediuminterface 928. The input device 929 includes, for example, a touchsensor configured to detect touch onto a screen of the display device930, a button, or a switch, and receives an operation or an informationinput from a user. The display device 930 includes a screen such as aLCD or an OLED display, and displays an image of the navigation functionor content that is reproduced. The speaker 931 outputs sound of thenavigation function or the content that is reproduced.

The radio communication interface 933 supports any cellularcommunication scheme such as LET and LTE, and performs radiocommunication. The radio communication interface 933 may typicallyinclude, for example, a BB processor 934 and an RF circuit 935. The BBprocessor 934 may perform, for example, encoding/decoding,modulating/demodulating, and multiplexing/demultiplexing, and performsvarious types of signal processing for radio communication. Meanwhile,the RF circuit 935 may include, for example, a mixer, a filter, and anamplifier, and transmits and receives radio signals via the antenna 937.The radio communication interface 933 may be a one chip module havingthe BB processor 934 and the RF circuit 935 integrated thereon. Theradio communication interface 933 may include the multiple BB processors934 and the multiple RF circuits 935, as illustrated in FIG. 15. Notethat FIG. 15 illustrates the example in which the radio communicationinterface 933 includes the multiple BB processors 934 and the multipleRF circuits 935, but the radio communication interface 933 may alsoinclude a single BB processor 934 or a single RF circuit 935.

Furthermore, in addition to a cellular communication scheme, the radiocommunication interface 933 may support another type of radiocommunication scheme such as a short-distance wireless communicationscheme, a near field communication scheme, and a radio LAN scheme. Inthat case, the radio communication interface 933 may include the BBprocessor 934 and the RF circuit 935 for each radio communicationscheme.

Each of the antenna switches 936 switches connection destinations of theantennas 937 among multiple circuits (such as circuits for differentradio communication schemes) included in the radio communicationinterface 933.

Each of the antennas 937 includes a single or multiple antenna elements(such as multiple antenna elements included in an MIMO antenna), and isused for the radio communication interface 933 to transmit and receiveradio signals. The car navigation apparatus 920 may include the multipleantennas 937, as illustrated in FIG. 15. Note that FIG. 15 illustratesthe example in which the car navigation apparatus 920 includes themultiple antennas 937, but the car navigation apparatus 920 may alsoinclude a single antenna 937.

Furthermore, the car navigation apparatus 920 may include the antenna937 for each radio communication scheme. In that case, the antennaswitches 936 may be omitted from the configuration of the car navigationapparatus 920.

The battery 938 supplies power to blocks of the car navigation apparatus920 illustrated in FIG. 15 via feeder lines that are partially shown asdashed lines in the figure. The battery 938 accumulates power suppliedform the vehicle.

The car navigation apparatus 920 illustrated in FIG. 15 may also operateas the master device of a secondary system. In this case, thecommunication control unit 240 described using FIG. 10 may beimplemented in the radio communication interface 933. Also, at leastsome of these functions may also be implemented in the processor 921.For example, by executing wireless communication with slave devicesusing transmit power allocated by the communication control apparatus100, the car navigation apparatus 920 is able to initiate the managementand operation of a secondary system promptly while also preventingharmful interference on the primary system. Additionally, the carnavigation apparatus 920 may also operate as a slave device of asecondary system.

The technology of the present disclosure may also be realized as anin-vehicle system (or a vehicle) 940 including one or more blocks of thecar navigation apparatus 920, the in-vehicle network 941, and avehicle-side module 942. The vehicle-side module 942 generates vehicledata such as vehicle speed, engine speed, and trouble information, andoutputs the generated data to the in-vehicle network 941.

8. Conclusion

The foregoing thus describes several embodiments of technology accordingto the present disclosure in detail using FIGS. 1 to 15. According tothe foregoing embodiments, in an apparatus that calculates the transmitpower that should be allocated to one or more secondary systems thatsecondarily use frequency channels protected for a primary system, whenthe number of secondary systems changes, whether to recalculate thetransmit power or adjust a previously calculated transmit power on thebasis of the variation in the number of secondary systems is determineddynamically in accordance with a condition dependent on the number ofsecondary systems. Consequently, it is possible to achieve bothprevention of harmful interference and promptness of power allocation.In addition, it is possible to resolve adverse effects, such as theproduction of harmful interference caused by power allocation not beingupdated in a timely manner. Consequently, the utilization efficiency ofradio resources is improved. Note that although this specificationdescribes an example in which primarily the recalculation and adjustmentof transmit power is conducted periodically, the technology according tothe present disclosure is not limited to such an example. For example,the transmit power may also be adjusted with a small calculation cost inaccordance with the technology of the present disclosure when a triggeris detected, such as a request from the primary system or a secondarysystem, or a change in some kind of input condition.

For example, the transmit power is recalculated when the changed numberof secondary systems falls below a threshold. On the other hand,adjustment of a previously calculated transmit power is executed whenthe changed number of secondary systems exceeds a threshold.Consequently, when many secondary systems are present, and there is apossibility that the calculation of power allocation may not finishwithin an allowed time, only adjustment of the transmit power isexecuted with a simple algorithm. Consequently, it is possible toprevent the loss of communication opportunities in a secondary systemcaused by a delay in the allocation of transmit power, while alsomaintaining the protection of the primary system.

According to a power calculation model given as an example, the transmitpower to allocate to each secondary system is calculated by using anominal transmit power of the relevant secondary system and aninterference avoidance margin. In this model, the adjustment of transmitpower is executed by adjusting the interference avoidance margin on thebasis of the variation in the number of secondary systems. Consequently,the transmit power may be adjusted with a small calculation cost, simplyby monitoring changes in the number of secondary systems.

Note that the series of control processing by the respective apparatusesdescribed herein may be implemented by using any of software, hardware,and a combination of software and hardware. Programs constituting thesoftware are previously stored in, for example, a recording medium (anon-transitory medium) provided in the inside or the outside of therespective apparatuses. And the respective programs are, for example,read into a random access memory (RAM) during execution and executed bythe processor such as the CPU.

Further, the processes described using the flowcharts in the presentdescription may not necessarily be executed in the order indicated bythe flowchart. Some process steps may be executed in parallel. Further,additional process steps may be employed, and some process steps may beomitted.

The preferred embodiment(s) of the present disclosure has/have beendescribed above with reference to the accompanying drawings, whilst thepresent disclosure is not limited to the above examples. A personskilled in the art may find various alterations and modifications withinthe scope of the appended claims, and it should be understood that theywill naturally come under the technical scope of the present disclosure.

In addition, the effects described in the present specification aremerely illustrative and demonstrative, and not limitative. In otherwords, the technology according to the present disclosure can exhibitother effects that are evident to those skilled in the art along with orinstead of the effects based on the present specification.

Additionally, the present technology may also be configured as below.

(1)

A communication control apparatus including:

a calculation unit configured to calculate a transmit power to beallocated to one or more secondary systems that secondarily usefrequency channels protected for a primary system; and

a determination unit configured to, when the number of secondary systemschanges, determine, according to a condition dependent on the number ofsecondary systems, whether to cause the calculation unit to recalculatethe transmit power or adjust a previously calculated transmit power onthe basis of the variation in the number of secondary systems.

(2)

The communication control apparatus according to (1), wherein

the determination unit causes the calculation unit to recalculate thetransmit power in a case of the changed number of secondary systemsfalling below a threshold value, and causes the calculation unit toadjust the previously calculated transmit power in a case of the changednumber of secondary systems exceeding the threshold value.

(3)

The communication control apparatus according to (2), wherein

the threshold value is configured in advance in a manner that anestimated calculation time dependent on the number of secondary systemsdoes not exceed an allowed calculation time.

(4)

The communication control apparatus according to (2), wherein

the threshold value is configured dynamically in a manner that anestimated calculation time dependent on the number of secondary systemsdoes not exceed an allowed calculation time.

(5)

The communication control apparatus according to any one of (1) to (4),wherein

the variation in the number of secondary systems is calculated on abasis of the number of secondary systems at a point in time when thetransmit power was last recalculated.

(6)

The communication control apparatus according to any one of (1) to (4),wherein

the variation in the number of secondary systems is calculated on abasis of the number of secondary systems at an immediately previouspoint in time when the transmit power was recalculated or adjusted.

(7)

The communication control apparatus according to any one of (1) to (6),wherein

the transmit power to be allocated to each secondary system includes anominal transmit power of the relevant secondary system and a margin forinterference avoidance, and

the calculation unit adjusts the transmit power by adjusting the marginfor interference avoidance on the basis of the variation in the numberof secondary systems.

(8)

The communication control apparatus according to (7), wherein

the calculation unit calculates an adjustment of the margin forinterference avoidance by estimating a variation in an interferencequantity on a basis of the variation in the number of secondary systems.

(9)

The communication control apparatus according to (8), wherein

the calculation unit estimates the variation in the interferencequantity by using a table defining mappings between the variation in thenumber of secondary systems and the variation in the interferencequantity.

(10)

The communication control apparatus according to (8), wherein

the calculation unit estimates the variation in the interferencequantity on a basis of an assumption that the number of secondarysystems and the interference quantity are proportional.

(11)

The communication control apparatus according to any one of (7) to (10),further including

a signaling unit configured to signal an adjustment of the margin forinterference avoidance calculated by the calculation unit to existingsecondary systems.

(12)

The communication control apparatus according to (11), wherein

the signaling unit signals a base value and the adjustment of the marginfor interference avoidance to new secondary systems.

(13)

The communication control apparatus according to (12), wherein

depending on the load on the calculation unit, the signaling unit causeseach relevant secondary system itself to calculate the nominal transmitpower by signaling calculation parameters to the new secondary systems.

(14)

The communication control apparatus according to any one of (1) to (13),wherein

the communication control apparatus has an authority to allocatetransmit power to the one or more secondary systems within a firstgeographical region, and

the calculation unit, in a case in which presence of secondary systemswithin a second geographical region neighboring the first geographicalregion should be considered in transmit power allocation, acquiresinformation indicating a number of secondary systems within the secondgeographical region that should be considered from another apparatushaving authority for the second geographical region.

(15)

The communication control apparatus according to any one of (11) to(13), wherein

the transmit power to be allocated to each secondary system additionallyincludes a margin for reducing signaling overhead, and

the signaling unit refrains from signaling the adjustment of the marginfor interference avoidance to the existing secondary systems in a caseof the adjustment of the margin for interference avoidance falling belowthe margin for reducing signaling overhead included in analready-allocated transmit power.

(16)

The communication control apparatus according to any one of (1) to (15),wherein

the calculation unit reduces the frequency of signaling to eachsecondary system by adjusting the transmit power by setting thevariation in the number of secondary systems to a greater-than-actualvirtual value.

(17)

A communication control method including:

in a processor, calculating a transmit power to be allocated to one ormore secondary systems that secondarily use frequency channels protectedfor a primary system; and

when the number of secondary systems changes, determining, according toa condition dependent on the number of secondary systems, whether tocause the processor to recalculate the transmit power or adjust apreviously calculated transmit power on the basis of the variation inthe number of secondary systems.

(18)

A wireless communication apparatus including:

a communication unit configured to communicate with a communicationcontrol apparatus that, when there is a change in the number ofsecondary systems operated and managed by secondarily using frequencychannels protected for a primary system, recalculates a transmit powerto be allocated to each secondary system or adjusts a previouslycalculated transmit power on the basis of the variation in the number ofsecondary systems, according to a condition depending on the number ofsecondary systems; and

a communication control unit configured to control wirelesscommunication between the wireless communication apparatus and one ormore terminal apparatuses according to the allocation of transmit powerindicated by the communication control apparatus via the communicationunit.

Additionally, the present technology may also be configured as below.

(1)

A communication control apparatus including:

a calculation unit configured to calculate a transmit power to beallocated, including a nominal transmit power and a margin forinterference avoidance, for one or more secondary systems thatsecondarily use frequency channels protected for a primary system; and

a determination unit configured to determine a variation in a number ofsecondary systems, and cause the calculation unit to adjust the marginfor interference avoidance on a basis of the determined variation.

(2)

The communication control apparatus according to (1), wherein

the determination unit determines, according to a condition dependent onthe number of secondary systems, whether to cause the calculation unitto recalculate the transmit power or adjust a previously calculatedtransmit power by adjusting the margin for interference avoidance on abasis of the variation.

(3)

The communication control apparatus according to (2), wherein

the determination unit causes the calculation unit to recalculate thetransmit power in a case of the changed number of secondary systemsfalling below a threshold value, and causes the calculation unit toadjust the previously calculated transmit power in a case of the changednumber of secondary systems exceeding the threshold value.

(4)

The communication control apparatus according to (3), wherein

the threshold value is configured in advance in a manner that anestimated calculation time dependent on the number of secondary systemsdoes not exceed an allowed calculation time.

(5)

The communication control apparatus according to (3), wherein

the threshold value is configured dynamically in a manner that anestimated calculation time dependent on the number of secondary systemsdoes not exceed an allowed calculation time.

(6)

The communication control apparatus according to any one of (2) to (5),wherein

the variation in the number of secondary systems is calculated on abasis of the number of secondary systems at a point in time when thetransmit power was last recalculated.

(7)

The communication control apparatus according to any one of (2) to (5),wherein

the variation in the number of secondary systems is calculated on abasis of the number of secondary systems at an immediately previouspoint in time when the transmit power was recalculated or adjusted.

(8)

The communication control apparatus according to any one of (1) to (7),wherein

the number of secondary systems is based on one or both of a number ofmaster devices and a number of slave devices in the secondary systems.

(9)

The communication control apparatus according to (8), wherein

the numbers of devices are calculated by including weights depending ona device configuration.

(10)

The communication control apparatus according to any one of (2) to (7),wherein

the determination unit additionally determines whether to cause thecalculation unit to recalculate the transmit power or adjust thepreviously calculated transmit power according to a condition dependenton at least one from among a reference point, a frequency channel to besecondarily used, a device antenna height, and an interference levelfrom other systems.

(11)

The communication control apparatus according to any one of (1) to (10),wherein

the calculation unit calculates an adjustment of the margin forinterference avoidance by estimating a variation in an interferencequantity on a basis of the variation in the number of secondary systems.

(12)

The communication control apparatus according to (11), wherein

the calculation unit estimates the variation in the interferencequantity by using a table defining mappings between the variation in thenumber of secondary systems and the variation in the interferencequantity.

(13)

The communication control apparatus according to (11), wherein

the calculation unit estimates the variation in the interferencequantity on a basis of an assumption that the number of secondarysystems and the interference quantity are proportional.

(14)

The communication control apparatus according to any one of (1) to (13),wherein

the communication control apparatus has an authority to allocatetransmit power to the one or more secondary systems within a firstgeographical region, and

the calculation unit, in a case in which presence of secondary systemswithin a second geographical region neighboring the first geographicalregion should be considered in transmit power allocation, acquiresinformation indicating a number of secondary systems within the secondgeographical region that should be considered from another apparatushaving authority for the second geographical region.

(15)

The communication control apparatus according to any one of (1) to (14),wherein

the calculation unit adjusts the margin for interference avoidance bysetting the variation in the number of secondary systems to agreater-than-actual virtual value.

(16)

The communication control apparatus according to any one of (1) to (15),further including

a signaling unit configured to signal an adjustment of the margin forinterference avoidance calculated by the calculation unit for thesecondary systems.

(17)

The communication control apparatus according to (16), wherein

the allocated transmit power for each secondary system additionallyincludes a margin for reducing signaling overhead, and

the signaling unit refrains from signaling the adjustment of the marginfor interference avoidance in a case of the adjustment of the margin forinterference avoidance falling below the margin for reducing signalingoverhead included in an already-allocated transmit power.

(18)

A communication control method including:

in a processor, calculating a transmit power to be allocated, includinga nominal transmit power and a margin for interference avoidance, forone or more secondary systems that secondarily use frequency channelsprotected for a primary system; and

determining a variation in a number of secondary systems, and causingthe processor to adjust the margin for interference avoidance on a basisof the determined variation.

(19)

A communication control apparatus including:

a communication unit configured to communicate with a master device ofone or more secondary systems that secondarily use frequency channelsprotected for a primary system; and

a control unit configured to signal, on a basis of information acquiredfrom a data server that calculates an allocated transmit power for thesecondary systems including a nominal transmit power and a margin forinterference avoidance adjusted on a basis of variation in a number ofsecondary systems, parameters for specifying the allocated transmitpower to the master device via the communication unit.

(20)

The communication control apparatus according to (19), wherein

the control unit calculates the allocated transmit power for each masterdevice from the nominal transmit power as well as a base value and anadjustment of the margin for interference avoidance, and signals theparameters for specifying the calculated allocated transmit power to themaster device.

(21)

The communication control apparatus according to (19), wherein

the parameters include parameters for calculating the nominal transmitpower.

(22)

A communication control method of a communication control apparatus thatcommunicates with a master device of one or more secondary systems thatsecondarily use frequency channels protected for a primary system, thecommunication control method including

signaling, on a basis of information acquired from a data server thatcalculates an allocated transmit power for the secondary systemsincluding a nominal transmit power and a margin for interferenceavoidance adjusted on a basis of variation in a number of secondarysystems, parameters for specifying the allocated transmit power to themaster device.

(23)

A wireless communication apparatus that operates and manages a secondarysystem that secondarily uses a frequency channel protected for a primarysystem, the wireless communication apparatus including:

a communication unit configured to receive signaling of parameters forspecifying an allocated transmit power based on information acquiredfrom a data server that calculates the allocated transmit power for thesecondary system including a nominal transmit power and a margin forinterference avoidance adjusted on a basis of variation in a number ofsecondary systems; and

a communication control unit configured to control wirelesscommunication between the wireless communication apparatus and one ormore terminal apparatuses according to the allocated transmit powerspecified using the parameters.

(24)

A communication control method of a wireless communication apparatusthat operates and manages a secondary system that secondarily uses afrequency channel protected for a primary system, the communicationcontrol method including:

receiving signaling of parameters for specifying an allocated transmitpower based on information acquired from a data server that calculatesthe allocated transmit power for the secondary system including anominal transmit power and a margin for interference avoidance adjustedon a basis of variation in a number of secondary systems; and

controlling wireless communication between the wireless communicationapparatus and one or more terminal apparatuses according to theallocated transmit power specified using the parameters.

REFERENCE SIGNS LIST

-   1, 2 communication control system-   10 primary transceiver-   100 communication control apparatus (GLDB)-   102 communication control apparatus (GLDB)-   104 communication control apparatus (WSDB)-   110 communication unit-   120 storage unit-   130 control unit-   132 determination unit-   134 calculation unit-   136 signaling unit-   20 wireless communication apparatus (master WSD)-   210 wireless communication unit-   220 network communication unit-   230 storage unit-   240 communication control unit

The invention claimed is:
 1. A communication control apparatuscomprising: circuitry configured to: allocate a transmit power for oneor more secondary systems that secondarily use frequency channelsallocated to a primary system; monitor activation requests received fromthe one or more secondary systems; determine a variation in a number ofone or more master devices which belong to a secondary system, whereinthe master devices are configured to operate according to atime-division scheme and communicate with slave devices that areconfigured to operate the same scheme; estimate an interference levelfrom the secondary systems to the primary system when the variation inthe number of the one or more master devices is greater than a thresholdvalue; and signal information indicating that an activation request isallowed to the one or more secondary systems.
 2. The communicationcontrol apparatus according to claim 1, wherein the circuitry is furtherconfigured to periodically calculate the transmit power for the one ormore secondary systems.
 3. The communication control apparatus accordingto claim 1, wherein the circuitry is further configured to calculate thetransmit power for the one or more secondary systems based oninformation reported by the one or more secondary systems.
 4. Thecommunication control apparatus according to claim 1, wherein thecircuitry is further configured to: determine a method to adjust theallocated transmit power according to a condition dependent on thenumber of one or more secondary systems; determine whether torecalculate a previously calculated transmit power or adjust thepreviously calculated transmit power by adjusting a margin forinterference avoidance based on the variation; and adjust the allocatedtransmit power based on the determined method.
 5. The communicationcontrol apparatus according to claim 4, wherein the circuitry is furtherconfigured to recalculate the previously calculated transmit power in acase of variation in a number of one or more secondary systems fallingbelow a threshold value, and adjust the previously calculated transmitpower in another case of the variation in the number of one or moresecondary systems exceeding the threshold value.
 6. The communicationcontrol apparatus according to claim 5, wherein the threshold value isconfigured in advance in a manner that an estimated calculation timedependent on the number of one or more secondary systems does not exceedan allowed calculation time.
 7. The communication control apparatusaccording to claim 5, wherein the threshold value is configureddynamically in a manner that an estimated calculation time dependent onthe number of one or more secondary systems does not exceed an allowedcalculation time.
 8. A communication method comprising: allocating, bycircuitry, a transmit power for one or more secondary systems thatsecondarily use frequency channels allocated to a primary system;monitoring activation requests received from the one or more secondarysystems; determining a variation in a number of one or more masterdevices which belong to a secondary system, wherein the master devicesare configured to operate according to a time-division scheme andcommunicate with slave devices that are configured to operate the samescheme; estimating an interference level from the secondary systems tothe primary system when the variation in the number of the one or moremaster devices is greater than a threshold value; and signalinginformation indicating that an activation request is allowed to the oneor more secondary systems.
 9. The communication method according toclaim 8, further comprising: periodically calculating the transmit powerfor the one or more secondary systems.
 10. The communication methodaccording to claim 8, further comprising: calculating the transmit powerfor the one or more secondary systems based on information reported bythe one or more secondary systems.
 11. The communication methodaccording to claim 8, further comprising: determining a method to adjustthe allocated transmit power according to a condition dependent on thenumber of one or more secondary systems; determining whether torecalculate a previously calculated transmit power or adjust thepreviously calculated transmit power by adjusting a margin forinterference avoidance based on the variation; and adjusting theallocated transmit power based on the determined method.
 12. Thecommunication method according to claim 11, further comprising:recalculating the previously calculated transmit power in a case ofvariation in a number of one or more secondary systems falling below athreshold value; and adjusting the previously calculated transmit powerin another case of the variation in the number of one or more secondarysystems exceeding the threshold value.
 13. The communication methodaccording to claim 12, wherein the threshold value is configured inadvance in a manner that an estimated calculation time dependent on thenumber of one or more secondary systems does not exceed an allowedcalculation time.
 14. The communication method according to claim 12,wherein the threshold value is configured dynamically in a manner thatan estimated calculation time dependent on the number of one or moresecondary systems does not exceed an allowed calculation time.
 15. Anon-transitory computer-readable storage medium storing executableinstructions which, when executed by circuitry, cause the circuitry toperform a communication method, the method comprising: allocating atransmit power for one or more secondary systems that secondarily usefrequency channels allocated to a primary system; monitoring activationrequests received from the one or more secondary systems; determining avariation in a number of one or more master devices which belong to asecondary system, wherein the master devices are configured to operateaccording to a time-division scheme and communicate with slave devicesthat are configured to operate the same scheme; estimating aninterference level from the secondary systems to the primary system whenthe variation in the number of the one or more master devices is greaterthan a threshold value; and signaling information indicating that anactivation request is allowed to the one or more secondary systems. 16.The non-transitory computer-readable storage medium according to claim15, wherein the method further comprises: periodically calculating thetransmit power for the one or more secondary systems.
 17. Thenon-transitory computer-readable storage medium according to claim 15,wherein the method further comprises: calculating the transmit power forthe one or more secondary systems based on information reported by theone or more secondary systems.
 18. The non-transitory computer-readablestorage medium according to claim 15, wherein the method furthercomprises: determining a method to adjust the allocated transmit poweraccording to a condition dependent on the number of one or moresecondary systems; determining whether to recalculate a previouslycalculated transmit power or adjust the previously calculated transmitpower by adjusting a margin for interference avoidance based on thevariation; and adjusting the allocated transmit power based on thedetermined method.
 19. The non-transitory computer-readable storagemedium according to claim 18, wherein the method further comprises:recalculating the previously calculated transmit power in a case ofvariation in a number of one or more secondary systems falling below athreshold value; and adjusting the previously calculated transmit powerin another case of the variation in the number of one or more secondarysystems exceeding the threshold value.
 20. The non-transitorycomputer-readable storage medium according to claim 19, wherein thethreshold value is configured in advance in a manner that an estimatedcalculation time dependent on the number of one or more secondarysystems does not exceed an allowed calculation time.
 21. Thenon-transitory computer-readable storage medium according to claim 19,wherein the threshold value is configured dynamically in a manner thatan estimated calculation time dependent on the number of one or moresecondary systems does not exceed an allowed calculation time.